Activation of parameter sets for multiview video coding (mvc) compatible three-dimensional video coding (3dvc)

ABSTRACT

In general, techniques are described for separately coding depth and texture components of video data. A video coding device for coding video data that includes a view component comprised of a depth component and a texture component may perform the techniques. The video coding device may comprise, as one example, a processor configured to activate a parameter set as a texture parameter set for the texture component of the view component, and code the texture component of the view component based on the activated texture parameter set.

This disclosure claims priority to U.S. Provisional Application No.61/565,376 filed 30 Nov. 2011, U.S. Provisional Application No.61/565,938 filed 1 Dec. 2011, U.S. Provisional Application No.61/579,631 filed 22 Dec. 2011, and U.S. Provisional Application No.61/584,009 filed 6 Jan. 2012, the contents of each of which is herebyincorporated by reference in its entirety.

TECHNICAL FIELD

This disclosure relates to video coding and, more particularly,three-dimensional video coding (3DVC).

BACKGROUND

Digital video capabilities can be incorporated into a wide range ofdevices, including digital televisions, digital direct broadcastsystems, wireless broadcast systems, personal digital assistants (PDAs),laptop or desktop computers, tablet computers, e-book readers, digitalcameras, digital recording devices, digital media players, video gamingdevices, video game consoles, cellular or satellite radio telephones,so-called “smart phones,” video teleconferencing devices, videostreaming devices, and the like. Digital video devices implement videocompression techniques, such as those described in the standards definedby MPEG-2, MPEG-4, ITU-T H.263, ITU-T H.264/MPEG-4, Part 10, AdvancedVideo Coding (AVC), the High Efficiency Video Coding (HEVC) standardpresently under development, and extensions of such standards. The videodevices may transmit, receive, encode, decode, and/or store digitalvideo information more efficiently by implementing such videocompression techniques.

Video compression techniques perform spatial (intra-picture) predictionand/or temporal (inter-picture) prediction to reduce or removeredundancy inherent in video sequences. For block-based video coding, avideo slice (i.e., a picture or a portion of a picture) may bepartitioned into video blocks, which may also be referred to astreeblocks, coding units (CUs) and/or coding nodes. Video blocks in anintra-coded (I) slice of a picture are encoded using spatial predictionwith respect to reference samples in neighboring blocks in the samepicture. Video blocks in an inter-coded (P or B) slice of a picture mayuse spatial prediction with respect to reference samples in neighboringblocks in the same picture or temporal prediction with respect toreference samples in other reference pictures.

Spatial or temporal prediction results in a predictive block for a blockto be coded. Residual data represents pixel differences between theoriginal block to be coded and the predictive block. An inter-codedblock is encoded according to a motion vector that points to a block ofreference samples forming the predictive block, and the residual dataindicating the difference between the coded block and the predictiveblock. An intra-coded block is encoded according to an intra-coding modeand the residual data. For further compression, the residual data may betransformed from the pixel domain to a transform domain, resulting inresidual transform coefficients, which then may be quantized. Thequantized transform coefficients, initially arranged in atwo-dimensional array, may be scanned in order to produce aone-dimensional vector of transform coefficients, and entropy coding maybe applied to achieve even more compression.

SUMMARY

In general, this disclosure describes techniques for three-dimensionalvideo coding (3DVC). More particularly, this disclosure describestechniques for performing 3DVC using a 3DVC extension of theH.264/Advanced Video Coding (AVC) standard. The 3DVC extension defines avideo coding technology for encoding multiple views of video data withdepth data. Each view may correspond to a different perspective, orangle, at which corresponding video data of a common scene was captured.In the context of 3DVC, each view may contain a texture view and a depthview. A coded representation of a view in one time instance is a viewcomponent. A view component may contain a depth view component and atexture view component. The techniques of this disclosure generallyrelate to enabling handling of both texture components and depthcomponents of a view for 3DVC when coding multiview video data plusdepth data. The techniques may promote compatibility of 3DVC with MVC.

In one example, a method of coding video data including a view componentcomprising a depth component and a texture component comprisesactivating a parameter set as a texture parameter set for the texturecomponent of the view component and coding the texture component of theview component based on the activated texture parameter set.

In another example, a video coding device for coding video dataincluding a view component comprised of a depth component and a texturecomponent comprises a processor configured to activate a parameter setas a texture parameter set for the texture component of the viewcomponent, and code the texture component of the view component based onthe activated texture parameter set.

In another example, a video coding device for coding video dataincluding a view component comprised of a depth component and a texturecomponent comprises means for activating a parameter set as a textureparameter set for the texture component of the view component and meansfor coding the texture component of the view component based on theactivated texture parameter set.

In another example, a non-transitory computer-readable storage mediumhas stored thereon instructions that, when executed, cause one or moreprocessors of a video coding device to activate a parameter set as atexture parameter set for the texture component of the view component,and code the texture component of the view component based on theactivated texture parameter set.

In another example, a method of processing video data including a viewcomponent comprises a depth component and a texture component isdescribed. The method comprises determining a supplemental enhancementinformation message that applies when processing the view component ofthe video data, and determining a nested supplemental enhancementinformation message that applies to the depth component of the viewcomponent in addition to the supplemental enhancement informationmessage.

In another example, a device for processing video data including a viewcomponent comprised of a depth component and a texture component isdescribed. The device comprises a processor configured to determine asupplemental enhancement information message that applies whenprocessing the view component of the video data, and determine a nestedsupplemental enhancement information message that applies in addition tothe supplemental enhancement information message when processing thedepth component of the view component.

In another example, a device for processing video data including a viewcomponent comprised of a depth component and a texture component isdescribed. The device comprises means for determining a supplementalenhancement information message that applies when processing the viewcomponent of the video data, and means for determining a nestedsupplemental enhancement information message that applies in addition tothe supplemental enhancement information message when processing thedepth component of the view component.

In another example, a non-transitory computer-readable storage mediumhas stored thereon instructions that, when executed, cause one or moreprocessors of a device for processing video data including a viewcomponent comprised of a depth component and a texture component todetermine a supplemental enhancement information message that applieswhen processing a view component of the video data, wherein the viewcomponent includes both a depth component and a texture component anddetermine a nested supplemental enhancement information message thatapplies in addition to the supplemental enhancement information messagewhen processing the depth component of the view component.

In another example, a method for video coding comprises storing a depthcomponent in a decoded picture buffer, analyzing a view dependency todetermine whether the depth component is used for inter-view predictionand removing the depth component from the decoded picture buffer inresponse to determining that the depth component is not used forinter-view prediction.

In another example, a video coding device configured to code video datacomprises a decoded picture buffer and a processor configured to store adepth component in the decoded picture buffer, analyze a view dependencyto determine whether the depth component is used for inter-viewprediction and remove the depth component from the decoded picturebuffer in response to determining that the depth component is not usedfor inter-view prediction.

In another example, a video coding device for coding video datacomprises means for storing a depth component in a decoded picturebuffer, means for analyzing a view dependency to determine whether thedepth component is used for inter-view prediction, and means forremoving the depth component from the decoded picture buffer in responseto determining that the depth component is not used for inter-viewprediction.

In another example, a non-transitory computer-readable storage mediumhas stored thereon instructions that, when executed, cause one or moreprocessors of a video coding device to store a depth component in adecoded picture buffer, analyze a view dependency to determine whetherthe depth component is used for inter-view prediction, and remove thedepth component from the decoded picture buffer in response todetermining that the depth component is not used for inter-viewprediction.

In another example, a method of processing video data including a viewcomponent comprising one or more depth components and one or moretexture components, the method comprises determining first sequencelevel information describing characteristics of the depth components,and determining second sequence level information describingcharacteristics of an operation point of the video data.

In another example, a video coding device for processing video dataincluding a view component comprising one or more depth components andone or more texture components is described. The video coding devicecomprises one or more processors configured to determine first sequencelevel information describing characteristics of the depth components,and determine second sequence level information describingcharacteristics of an operation point of the video data.

In another example, a video coding device for processing video dataincluding a view component comprising one or more depth components andone or more texture components is described. The video coding devicecomprises means for determining first sequence level informationdescribing characteristics of the depth components and means fordetermining second sequence level information describing characteristicsof an operation point of the video data.

In another example, a non-transitory computer-readable storage mediumhas stored thereon instructions that, when executed, cause one or moreprocessors of a video coding device to determine first sequence levelinformation describing characteristics of one or more depth componentsof video data, wherein the video data includes a view componentcomprising the one or more depth components and one or more texturecomponents and determine second sequence level information describingcharacteristics of an operation point of the video data.

The details of one or more aspects of the disclosure are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the techniques described in this disclosurewill be apparent from the description and drawings, and from the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating an example video encoding anddecoding system that may utilize the techniques described in thisdisclosure.

FIG. 2 is a block diagram illustrating the video encoder shown in theexample of FIG. 1 in more detail.

FIG. 3 is a block diagram illustrating the video decoder shown in theexample of FIG. 1 in more detail.

FIG. 4 is a block diagram illustrating the encapsulation unit shown inthe example of FIG. 1 in more detail.

FIG. 5 is a conceptual diagram illustrating an example Multiview VideoCoding (MVC) prediction pattern.

FIG. 6 is a flow diagram illustrating operation of a video coding devicein implementing parameter set activation for MVC-compatible 3DVC inaccordance with various aspects of the techniques described in thisdisclosure.

FIG. 7 is a flow diagram illustrating example operation of processingmultiview video data to generate nested supplemental enhancementinformation (SEI) messages for MVC-compatible 3DVC in accordance withthe techniques described in this disclosure.

FIG. 8 is a flow diagram illustrating example operation of a videocoding device in separately removing texture and depth components from adecoded picture buffer for MVC-compatible 3DVC in accordance with thetechniques described in this disclosure.

FIG. 9 is a flow diagram illustrating example operation of a videocoding device in determining sequence level information forMVC-compatible 3DVC in accordance with the techniques described in thisdisclosure.

DETAILED DESCRIPTION

According to certain video coding systems, motion estimation and motioncompensation may be used to reduce the temporal redundancy in a videosequence, so as to achieve data compression. In this case, a motionvector can be generated that identifies a predictive block of videodata, e.g., a block from another video picture or slice, which can beused to predict the values of the current video block being coded. Thevalues of the predictive video block are subtracted from the values ofthe current video block to produce a block of residual data. Motioninformation (e.g., a motion vector, motion vector indexes, predictiondirections, or other information) is communicated from a video encoderto a video decoder, along with the residual data. The decoder can locatethe same predictive block (based on the motion vector) and reconstructthe encoded video block by combining the residual data with the data ofthe predictive block.

Multiview Video Coding (MVC) is a video coding process for codingmultiple views of video data. In general, each view corresponds to adifferent perspective, or angle, at which corresponding video data of acommon scene was captured. Three dimensional video coding (3DVC) may beperformed using MVC plus depth coding. A 3DVC extension to the ITU-TH.264/AVC standard is presently under development. A working draft of anamendment to the H.264/AVC standard to add the 3DVC extension isdescribed in “WD on MVC Extensions for Inclusion of Depth Maps,”ISO/IEC/JTC1/SC29/WG11/N12351, Geneva, Switzerland, dated November 2011(“3DVC WD”). The 3DVC extension, also referred to as MVC extensions forinclusion of depth maps, defines techniques for coding views to supportdisplay of 3D video data.

For example, in 3D video, two views (e.g., left and right eye views of ahuman viewer) may be displayed simultaneously or near simultaneouslyusing different polarizations of light, and a viewer may wear passive,polarized glasses such that each of the viewer's eyes receives arespective one of the views. Alternatively, the viewer may wear activeglasses that shutter each eye independently, and a display may rapidlyalternate between images of each eye in synchronization with theglasses.

While each view (e.g., left and right eye views) may be individuallycoded, in 3DVC, one of the views is reconstructed from the other viewusing a depth component of the view. For this reason, this form of 3DVCmay also be referred to as multiview video coding plus depth (MVC+D). Toillustrate, a depth map of a particular picture of a view (where thisparticular picture of a view may be referred to as a “view component” ofthe view) may be computed as a difference between the left eye view andthe right eye view. The encoder may encode the left eye view, forexample, as a so-called “texture component” of the view component andthe depth map may be encoded as a so-called “depth component” of theview component.

The decoder may then decode the texture component of the view componentand the depth component of the view component and reconstruct the righteye view from the texture component (which represents the left eye view)using the depth component. By encoding only one view and a correspondingdepth map in this manner, 3DVC may more efficiently encode both the lefteye and right eye view in comparison to encoding both the left eye viewand the right eye view independently as separate views of the 3DVC data.

When encoding the texture and depth components of a view, the videoencoder typically handles or otherwise processes both the texture anddepth components as view components without providing any way by whichto distinguish between texture and depth components. That is, 3DVCprovides for handling or coding of view components without providing away by which to individually process texture components separately fromdepth components of the same view component. This lack of distinction in3DVC may result in less coding efficiency and/or lower quality ofreconstructed video data.

For example, a depth component may currently be required to be specifiedat the same resolution as a corresponding texture component so as toaccommodate joint handling of this view component. A higher resolutiondepth component (in comparison to the resolution of the texturecomponent) may, however, result in three-dimensional (3D) video playbackin that a better, more immersive 3D video may result that better mimicswhat a viewer's visual system expects. Moreover, a lower resolutiondepth component (compared to the resolution of the texture component)may provide the same or similar immersive 3D experience in certaininstances but consume less bits when coded and thereby increase codingefficiency. By failing to enable separate handling of depth and texturecomponents, 3DVC may reduce coding efficiency and/or provide for lowerquality of reconstructed video data (often, in terms, of the viewingexperience).

The techniques of this disclosure generally relate to enabling separateor independent handling of texture components and depth components of aview when processing or coding 3DVC video data. For example, thisdisclosure proposes signaling picture size of a depth map sequence in asequence parameter set (SPS). These signaling techniques may be appliedby an encoder and used by a decoder during the video encoding and/ordecoding process. The described techniques are related to the coding ofpictures of video content. The encoded pictures may have a unit size,such as a block of a selected height and width, which may be signaled assyntax elements in a sequence parameter set, in accordance with thetechniques of this disclosure. Syntax elements for texture viewsequences and depth map sequences may be signaled in a sequenceparameter set.

More specifically, the techniques involve signaling syntax informationwhen a depth map sequence has a different resolution than thecorresponding texture view sequence. 3DVC may include coding multipleviews with a depth map sequence for each view. These depth map sequencesmay have a different resolution than the texture view sequences. In thiscase, the depth view component and the texture view component cannotshare the same sequence parameter set (SPS) when the texture and depthnetwork abstraction layer (NAL) units are simply multiplexed together.It may not be possible to indicate different levels, with or withoutdepth, in the current SPS MVC extension. In the AVC design principle, itmay not be possible to activate more than one sequence parameter set,which contains the picture size. Thus, having two different picturesizes might result in activating multiple sequence parameter sets.

Techniques of the present disclosure can be used to indicate a 3DVCsequence based on AVC and MVC stereo, when the 3DVC sequence includes adepth map with a different spatial resolution than a correspondingtexture view. By enabling such independent handling, the various aspectsof the techniques described in this disclosure may promote bit savings(or, in other words, more efficient coding of multiview video data)and/or better quality of reconstructed video data (which again may bemeasured in terms of a perceived viewing experience).

The following description should be understood to be in the context of3DVC, where reference to MVC is understood to be reference to MVC as itrelates to MVC plus depth coding in the 3DVC extension. That is, giventhat MVC is an extension to H.264, and 3DVC is a further extension ofH.264 that makes use of MVC, 3DVC incorporates or otherwise may beconsidered to “inherit” all aspects of MVC. 3DVC may extend or otherwiseadd to MVC where appropriate in the manner described herein to providefor a MVC-compliant bitstream that also includes depth maps for thosevideo decoders that support 3DVC. In other words, in some examples, thetechniques may provide for generation of a 3DVC bitstream that isbackwards compatible with MVC (or, in other words, capable of beingdecoded by a video decoder that does not support 3DVC but that doessupport MVC). While the following techniques are each described in thecontext of 3DVC, these techniques may be extended in some instances toother ways of coding 3D video data having both texture view componentsand depth view components.

FIG. 1 is a block diagram illustrating an example video encoding anddecoding system 10 that may utilize techniques for motion vectorprediction in multiview coding. As shown in FIG. 1, system 10 includes asource device 12 that provides encoded video data to be decoded at alater time by a destination device 14. In particular, source device 12provides the video data to destination device 14 via a computer-readablemedium 16. Source device 12 and destination device 14 may comprise anyof a wide range of devices, including desktop computers, notebook (i.e.,laptop) computers, tablet computers, slate computers, set-top boxes,telephone handsets such as so-called “smart” phones, so-called “smart”pads, televisions, cameras, display devices, digital media players,video gaming consoles, video streaming device, or the like. In somecases, source device 12 and destination device 14 may be equipped forwireless communication.

Destination device 14 may receive the encoded video data to be decodedvia computer-readable medium 16. Computer-readable medium 16 maycomprise any type of medium or device capable of transferring theencoded video data from source device 12 to destination device 14. Inone example, computer-readable medium 16 may comprise a communicationmedium to enable source device 12 to transmit encoded video datadirectly to destination device 14 in real-time or near real-time.

The encoded video data may be modulated according to a communicationstandard, such as a wireless communication protocol, and transmitted todestination device 14. The communication medium may comprise anywireless or wired communication medium, such as a radio frequency (RF)spectrum or one or more physical transmission lines. The communicationmedium may form part of a packet-based network, such as a local areanetwork, a wide-area network, or a global network such as the Internet.The communication medium may include routers, switches, base stations,or any other equipment that may be useful to facilitate communicationfrom source device 12 to destination device 14.

In some examples, encoded data may be output from transmitter 24 ofsource device 24 to a storage device. Similarly, encoded data may beaccessed from the storage device by receiver 26 of destination device14. The storage device may include any of a variety of distributed orlocally accessed data storage media such as a hard drive, Blu-ray discs,DVDs, CD-ROMs, flash memory, volatile or non-volatile memory, or anyother suitable digital storage media for storing encoded video data. Ina further example, the storage device may correspond to a file server oranother intermediate storage device that may store the encoded videogenerated by source device 12.

Destination device 14 may access stored video data from the storagedevice via streaming or download. The file server may be any type ofserver capable of storing encoded video data and transmitting thatencoded video data to the destination device 14. Example file serversinclude a web server (e.g., for a website), an FTP server, networkattached storage (NAS) devices, or a local disk drive. Destinationdevice 14 may access the encoded video data through any standard dataconnection, including an Internet connection. This may include awireless channel (e.g., a Wi-Fi connection), a wired connection (e.g.,DSL, cable modem, etc.), or a combination of both that is suitable foraccessing encoded video data stored on a file server. The transmissionof encoded video data from the storage device may be a streamingtransmission, a download transmission, or a combination thereof.

The techniques of this disclosure are not necessarily limited towireless applications or settings. The techniques may be applied tovideo coding in support of any of a variety of multimedia applications,such as over-the-air television broadcasts, cable televisiontransmissions, satellite television transmissions, Internet streamingvideo transmissions, such as dynamic adaptive streaming over HTTP(DASH), digital video that is encoded onto a data storage medium,decoding of digital video stored on a data storage medium, or otherapplications. In some examples, system 10 may be configured to supportone-way or two-way video transmission to support applications such asvideo streaming, video playback, video broadcasting, and/or videotelephony.

In the example of FIG. 1, source device 12 includes a video source 18, avideo encoder 20, an encapsulation unit 21, and an output interface 22.Destination device 14 includes input interface 28, decapsulation unit29, video decoder 30, and display device 32. In some examples, sourcedevice 12 and destination device 14 may include other components orarrangements. For example, source device 12 may receive video data froman external video source 18, such as an external camera. Likewise,destination device 14 may interface with an external display device,rather than including integrated display device 32.

The illustrated system 10 of FIG. 1 is merely one example. Techniquesfor motion vector prediction in multiview coding (including 3DVC) may beperformed by any digital video encoding and/or decoding device. Althoughgenerally the techniques of this disclosure are performed by a videoencoding device, the techniques may also be performed by a videoencoder/decoder, typically referred to as a “CODEC.” Moreover, thetechniques of this disclosure may also be performed by a videopreprocessor. Source device 12 and destination device 14 are merelyexamples of such coding devices in which source device 12 generatescoded video data for transmission to destination device 14. In someexamples, devices 12, 14 may operate in a substantially symmetricalmanner such that each of devices 12, 14 include video encoding anddecoding components. Hence, system 10 may support one-way or two-wayvideo transmission between video devices 12, 14, e.g., for videostreaming, video playback, video broadcasting, or video telephony.

Video source 18 of source device 12 may include a video capture device,such as a video camera, a video archive containing previously capturedvideo, and/or a video feed interface to receive video from a videocontent provider. As a further alternative, video source 18 may generatecomputer graphics-based data as the source video, or a combination oflive video, archived video, and computer-generated video. In some cases,if video source 18 is a video camera, source device 12 and destinationdevice 14 may form so-called camera phones or video phones. As mentionedabove, however, the techniques described in this disclosure may beapplicable to video coding in general, and may be applied to wirelessand/or wired applications. In each case, the captured, pre-captured, orcomputer-generated video may be encoded by video encoder 20. The encodedvideo information may then be output by output interface 22 onto acomputer-readable medium 16.

Video source 24 may generally provide a plurality of views of a scene tovideo encoder 28. Video source 24 may also provide informationindicative of locations of camera perspectives for the views. Videosource 24 may provide this information to video encoder 28, or mayprovide the information directly to encapsulation unit 21.

Encapsulation unit 21 may use the information indicative of relativelocations of camera perspectives for the views to assign viewidentifiers to views of multimedia content. Encapsulation unit 21 mayform one or more representations of the multimedia content, where eachof the representations may include one or more views. In some examples,video encoder 20 may encode each view in different ways, e.g., withdifferent frame rates, different bit rates, different resolutions, orother such differences. Thus, encapsulation unit 21 may form variousrepresentations having various characteristics, e.g., bit rate, framerate, resolution, and the like.

Each of the representations may correspond to respective bitstreams thatcan be retrieved by destination device 14. Encapsulation unit 21 mayprovide an indication of a range of view identifiers (view_ids) forviews included in each representation, e.g., within a media presentationdescription (MPD) data structure for the multimedia content. Forexample, encapsulation unit 21 may provide an indication of a maximumview identifier and a minimum view identifier for the views of arepresentation. The MPD may further provide indications of maximumnumbers of views targeted for output for each of a plurality ofrepresentations of the multimedia content. The MPD or data thereof may,in some examples, be stored in a manifest for the representation(s).

Computer-readable medium 16 may include transient media, such as awireless broadcast or wired network transmission, or storage media (thatis, non-transitory storage media), such as a hard disk, flash drive,compact disc, digital video disc, Blu-ray disc, or othercomputer-readable media. In some examples, a network server (not shown)may receive encoded video data from source device 12 and provide theencoded video data to destination device 14, e.g., via networktransmission. Similarly, a computing device of a medium productionfacility, such as a disc stamping facility, may receive encoded videodata from source device 12 and produce a disc containing the encodedvideo data. Therefore, computer-readable medium 16 may be understood toinclude one or more computer-readable media of various forms, in variousexamples.

Input interface 28 of destination device 14 receives information fromcomputer-readable medium 16. The information of computer-readable medium16 may include syntax information defined by video encoder 20, which isalso used by video decoder 30, that includes syntax elements thatdescribe characteristics and/or processing of blocks and other codedunits, e.g., GOPs. Decapsulation unit 29 of destination device 14 mayrepresent a unit that decapsulates SEI messages from a bitstream (or asubset of a bitstream referred to as an “operation point” in the contextof MVC). Decapsulation unit 29 may perform operations in an orderopposite those performed by encapsulation unit 29 to decapsulate datafrom the encapsulated encoded bitstream, such as SEI messages. Displaydevice 32 displays the decoded video data to a user, and may compriseany of a variety of display devices such as a cathode ray tube (CRT), aliquid crystal display (LCD), a plasma display, an organic lightemitting diode (OLED) display, or another type of display device.

Video encoder 20 and video decoder 30 each may be implemented as any ofa variety of suitable encoder or decoder circuitry, as applicable, suchas one or more microprocessors, digital signal processors (DSPs),application specific integrated circuits (ASICs), field programmablegate arrays (FPGAs), discrete logic circuitry, software, hardware,firmware or any combinations thereof. Each of video encoder 20 and videodecoder 30 may be included in one or more encoders or decoders, eitherof which may be integrated as part of a combined video encoder/decoder(CODEC). A device including video encoder 20 and/or video decoder 30 maycomprise an integrated circuit, a microprocessor, and/or a wirelesscommunication device, such as a cellular telephone.

Although not shown in FIG. 1, in some aspects, video encoder 20 andvideo decoder 30 may each be integrated with an audio encoder anddecoder, and may include appropriate MUX-DEMUX units, or other hardwareand software, to handle encoding of both audio and video in a commondata stream or separate data streams. If applicable, MUX-DEMUX units mayconform to the ITU H.223 multiplexer protocol, or other protocols suchas the user datagram protocol (UDP).

In the example shown in FIG. 1, system 10 also includes server/contentdelivery network 34 having router 36. In some examples, source device 12may communicate with server/content delivery network 34 via a variety ofwireless and/or wired transmission or storage media, as described above.Moreover, while shown separately in the example of FIG. 1, in someexamples, source device 12 and server/content delivery network 34comprise the same device. Server/content delivery network 34 may storeone or more versions of coded video data (from video encoder 20 ofsource device 12), and may make such coded video data available foraccess by destination device 14 and video decoder 30. In some examples,router 36 may be responsible for providing coded video data todestination device 14 in a requested format.

Video encoder 20 and video decoder 30 may operate according to a videocoding standard, such as the High Efficiency Video Coding (HEVC)standard presently under development, and may conform to the HEVC TestModel (HM). Alternatively, video encoder 20 and video decoder 30 mayoperate according to other proprietary or industry standards, such asthe ITU-T H.264 standard, alternatively referred to as MPEG-4, Part 10,Advanced Video Coding (AVC), or extensions of such standards, includingthe MVC extension and/or 3DVC extension to H.264. The techniques of thisdisclosure, however, are not limited to any particular coding standard.Other examples of video coding standards include MPEG-2 and ITU-T H.263.

The ITU-T H.264/MPEG-4 (AVC) standard was formulated by the ITU-T VideoCoding Experts Group (VCEG) together with the ISO/IEC Moving PictureExperts Group (MPEG) as the product of a collective partnership known asthe Joint Video Team (JVT). In some aspects, the techniques described inthis disclosure may be applied to devices that generally conform to theH.264 standard. The H.264 standard is described in ITU-T RecommendationH.264, Advanced Video Coding for generic audiovisual services, by theITU-T Study Group, and dated March, 2005, which may be referred toherein as the H.264 standard or H.264 specification, or the H.264/AVCstandard or specification. H.264/AVC includes a scalable video coding(SVC) extensions and MVC extensions. In addition, there is furtherdevelopment to provide a 3DVC extension, making use of MVC withinclusion of depth maps. The Joint Video Team (JVT) continues to work onextensions to H.264/MPEG-4 AVC. While described within the context of3DVC, the techniques described in this disclosure may be implementedwith respect to other video coding algorithms capable of encoding anddecoding 3D video involving both texture and depth components.

Video encoder 20 may send syntax data, such as block-based syntax data,picture-based syntax data, and GOP-based syntax data, to video decoder30, e.g., in a picture header, a block header, a slice header, or a GOPheader. The GOP syntax data may describe a number of pictures in therespective GOP, and the picture syntax data may indicate anencoding/prediction mode used to encode the corresponding picture.

In some examples, video encoder 20 may generate and video decoder 30 mayreceive certain parameter sets, which may be used when decoding videodata. For example, parameter sets may contain sequence-level headerinformation (in sequence parameter sets (SPS)) and the infrequentlychanging picture-level header information (in picture parameter sets(PPS)). With parameter sets (e.g., PPS and SPS), infrequently changinginformation need not to be repeated for each sequence (e.g., sequence ofpictures) or picture; hence coding efficiency may be improved.Furthermore, the use of parameter sets may enable out-of-bandtransmission of the important header information, avoiding the need forredundant transmissions for error resilience. In out-of-bandtransmission examples, parameter set NAL units may be transmitted on adifferent channel than other NAL units, such as Supplemental EnhancementInformation (SEI) NAL units.

SEI NAL units (referred to as SEI messages) may contain information thatis not necessary for decoding the coded pictures samples from videocoding layer (VCL) NAL units, but may assist in processes related todecoding, display, error resilience, and other purposes. SEI messagesmay be contained in non-VCL NAL units. SEI messages may be included inthe normative part of some standard specifications, and thus are notalways mandatory for standard compliant decoder implementation. SEImessages may be sequence level SEI messages or picture level SEImessages. Some sequence level information may be contained in SEImessages, such as scalability information SEI messages in the example ofSVC and view scalability information SEI messages in MVC. Viewscalability information SEI messages also may provide sequence levelinformation for the 3DVC extension to H.264. Encapsulation unit 21 mayform these SEI messages and provide these SEI messages to server/contentdelivery network 34 for use in negotiating, as one example, delivery ofencoded video data.

Encapsulation unit 30 may form NAL units comprising a header thatidentifies a program to which the NAL belongs, as well as a payload,e.g., audio data, video data, or data that describes the transport orprogram stream to which the NAL unit corresponds. For example, inH.264/AVC, a NAL unit includes a 1-byte header and a payload of varyingsize. In one example, a NAL unit header comprises a priority_id element,a temporal_id element, an anchor_pic_flag element, a view_id element, anon_idr_flag element, and an inter_view_flag element. In conventionalMVC, the NAL unit defined by H.264 is retained, except for prefix NALunits and MVC coded slice NAL units, which include a 4-byte MVC NAL unitheader and the NAL unit payload.

In some examples, video encoder 20 may encode a 3DVC bitstream thatconforms to the 3DVC extension of H.264, using MVC plus depthinformation. The latest joint draft of MVC is described in “Advancedvideo coding for generic audiovisual services,” ITU-T RecommendationH.264, March 2010, while a working draft of 3DVC is described in “WD onMVC Extensions for Inclusion of Depth Maps,”ISO/IEC/JTC1/SC29/WG11/N12351, Geneva, Switzerland, dated November 2011,described above. Again, reference within this disclosure to MVC shouldbe understood to be a reference to MVC plus depth within the context of3DVC. That is, MVC is referred to in this disclosure as it relates to3DVC in the sense that 3DVC incorporates or “builds off” of MVC.

In the 3DVC extension to H.264, a view includes texture and depth. Thetexture part of a view is named the texture view, and the depth part ofa view is named the depth view. The texture part of a view in one accessunit, i.e., a texture view in an access unit, is named the texture viewcomponent. The depth part of a view in one access unit, i.e., a depthview in an access unit, is named the depth view component. The term viewcomponent is a view in one access unit and collectively refers to boththe texture view component and the depth view component in the sameaccess unit.

In the extensions of H.264/AVC, syntax elements may be added in the NALunit header extension to extend the NAL unit header from one byte tofour bytes to describe the characteristics of a VCL NAL unit in multipledimensions. Thus, a VCL NAL unit in the MVC extension may include alonger NAL unit header than the NAL unit header in the H.264/AVCstandard. The MVC extension to H.264/AVC may be referred to in thisdisclosure as “MVC/AVC.”

An MVC/AVC NAL unit may contain a one-byte NAL unit header that includesthe NAL unit type, as well as an MVC/AVC NAL unit header extension. Asone example, the MVC/AVC NAL unit header extension may include thesyntax elements in the following table:

NAL UNIT HEADER EXTENSION SYNTAX nal_unit_header_extension( ) { CDescriptor reserved_zero_bit All u(1) idr_flag All u(1) priority_id Allu(6) view_id All u(10) temporal_id All u(3) anchor_pic_flag All u(1)inter_view_flag All u(1) reserved_one_bit All u(1) }

In the above table, the idr_flag element may indicate whether the NALunit belongs to an instantaneous decoder refresh (IDR) or a view-IDR(V-IDR) picture that can be used as a closed-GOP random access point.For example, an IDR picture and all of the pictures succeeding the IDRpicture in both a display order and bitstream order can be properlydecoded without decoding previous pictures in either bitstream order ordisplay order.

The priority_id element may be used with a bitstream adaptation processthat varies the bitstream according to changing network conditionsand/or capabilities of video decoder 30 and/or display device 32 (e.g.,such as single-pass adaptation process). The view_id element may be usedto indicate the view identifier for the view to which the NAL unitbelongs, which may be used inside an MVC decoder, e.g., for inter-viewprediction and outside a decoder, e.g., for rendering. In someinstances, the view_id may be set equal to a predefined camera id, andmay be relatively large. The temporal_id element may be used to indicatethe temporal level of the current NAL unit, which may correspond to aparticular frame rate.

The anchor_pic_flag element may be used to indicate whether the NAL unitbelongs to an anchor picture that can be used as an open-GOP randomaccess point. For example, anchor pictures and all the picturessucceeding the anchor picture in display order may be properly decodedwithout decoding previous pictures in the decoding order (i.e. bitstreamorder) and thus may be used as random access points. Anchor pictures andnon-anchor pictures may have different view dependencies, both of whichmay be signaled in an SPS.

That is, as described herein a, a view dependency may generally refer toa view from which a view currently being coded depends. In other words,view dependencies may set forth from which views a view currently beingcoded may be predicted. According to some examples, view dependency maybe signaled in the SPS MVC extension. In such examples, all inter-viewprediction may be done within the scope specified by the SPS MVCextension. The inter_view_flag element may be used to indicate whetherthe NAL unit is used for inter-view prediction for NAL units in otherviews.

To convey the NAL unit header information (which may be four-bytes) forthe base view of an MVC bitstream, a prefix NAL unit may be defined inMVC. In the context of MVC, the base view access unit may include theVCL NAL units of a current time instance of a particular view, as wellas a prefix NAL unit for the base view access unit, which may containonly the NAL unit header. If the prefix NAL unit is not required fordecoding (e.g., such as decoding a single view), a decoder may ignoreand/or discard the prefix NAL unit.

With respect to an SPS MVC/AVC extension, the MVC SPS may indicate viewsthat may be used for purposes of inter-view prediction. For example,potential inter-view references may be signaled in and SPS MVC/AVCextension, and may be modified by the reference picture listconstruction process, which enables flexible ordering of the interprediction or inter-view prediction references. An example MVC/AVC SPSis set forth in the table below:

EXAMPLE MVC SPS seq_parameter_set_mvc_extension( ) { C Descriptornum_views_minus1 0 ue(v) for( i = 0; i <= num_views_minus1; i++ )view_id[ i ] 0 ue(v) for( i = 1; i <= num_views_minus1; i++ ) {num_anchor_refs_l0[ i ] 0 ue(v) for( j = 0; j < num_anchor_refs_l0[ i ];j++ ) anchor_ref_l0[ i ][ j ] 0 ue(v) num_anchor_refs_l1[ i ] 0 ue(v)for( j = 0; j < num_anchor_refs_l1[ i ]; j++ ) anchor_ref_l1[ i ][ j ] 0ue(v) } for( i = 1; i <= num_views_minus1; i++ ) {num_non_anchor_refs_l0[ i ] 0 ue(v) for( j = 0; j <num_non_anchor_refs_l0[ i ]; j++ ) non_anchor_ref_l0[ i ][ j ] 0 ue(v)num_non_anchor_refs_l1[ i ] 0 ue(v) for( j = 0; j <num_non_anchor_refs_l1[ i ]; j++ ) non_anchor_ref_l1[ i ][ j ] 0 ue(v) }num_level_values_signalled_minus1 0 ue(v) for( i = 0; i <=num_level_values_signalled_minus1; i++ ) { level_idc[ i ] 0 u(8)num_applicable_ops_minus1[ i ] 0 ue(v) for( j = 0; j <=num_applicable_ops_minus1[ i ]; j++ ) { applicable_op_temporal_id[ i ][j ] 0 u(3) applicable_op_num_target_views_minus1[ i ][ j ] 0 ue(v) for(k = 0; k <= applicable_op_num_target_views_minus1[ i ][ j ]; k++ )applicable_op_target_view_id[ i ][ j ][ k ] 0 ue(v)applicable_op_num_views_minus1[ i ][ j ] 0 ue(v) } } }

According to some examples, view dependency may be signaled in the SPSMVC extension. All inter-view prediction may be done within the scopespecified by the SPS MVC extension. That is, the SPS may set forth whichviews may be referred to for purposes of prediction by a view currentlybeing coded. In Table 2 above, the num_anchor_refs_10[i] element mayspecify the number of view components for inter-view prediction in theinitialized reference picture list for List 0 (e.g., RefPicList0).

In addition, the anchor_ref_10[i][j] element may specify the view_id ofthe j-th view component for inter-view prediction in the initializedRefPicList0. The num_anchor_refs_11[i] element may specify the number ofview components for inter-view prediction in the initialized referencepicture list for list one (e.g., RefPicList1). The anchor_ref_11[i][j]element may specify the view_id of the j-th view component forinter-view prediction in the initialized RefPicList1.

The num_non_anchor_refs_10[i] element may specify the number of viewcomponents for inter-view prediction in the initialized RefPicList0. Thenon_anchor_ref_10[i][j] element may specify the view_id of the j-th viewcomponent for inter-view prediction in the initialized RefPicList0. Thenum_non_anchor_refs_11[i] element may specify the number of viewcomponents for inter-view prediction in the initialized RefPicList1. Thenon_anchor_ref_11[i][j] element may specify the view_id of the j-th viewcomponent for inter-view prediction in the initialized RefPicList.

The initialized, or “initial”, reference picture list may be the same ordifferent from a final reference picture list used for purposes ofinter-view predicting view components. That is, certain referencecandidates (i.e., reference pictures that may be used for inter-viewprediction) may be removed from an initial reference picture list (e.g.,redundant pictures). In addition, as described in greater detail below,reference candidates may be reordered from the initial reference picturelist to form the final reference picture list.

In this example, according to MVC, view dependencies for anchor picturesand non-anchor pictures are separately maintained and signaled. That is,a video coder may determine a total of four reference picture lists(e.g., List 0, non-anchor pictures; List 1, non-anchor pictures; List 0,anchor pictures; List 1, anchor pictures). In addition, as shown inTable 2 above, separate signaling is required to indicate a viewdependency to video decoder 30. That is, the SPS must include separateList 0 and List 1 signaling for both anchor_refs and non_anchor_refs.

Moreover, according to Table 2, the inter-view dependency for non-anchorview components is a subset of that for anchor view components. That is,for example, a view component of an anchor view may be predicted frommore than one other view, such as view 3 and 4. A non-anchor view,however, may only be predicted from pictures of view 3 (a subset of theanchor view). In this way, the view dependencies for anchor andnon-anchor view components may be separately maintained.

In addition, in Table 2, the num_level_values_signalled may specify thenumber of level values signaled for the coded video sequence. Thelevel_idc[i] element may specify the i-th level value signaled for thecoded video sequence. The num_applicable_ops_minus1[i] plus 1 elementmay specify the number of operation points to which the level indicatedby level_idc1[i] applies. The applicable_op_temporal_id[i][j] elementmay specify the temporal_id of the j-th operation point to which thelevel indicated by level_idc[i] applies.

The applicable_op_num_target_views_minus1[i][j] element may specify thenumber of target output views for the j-th operation point to which thelevel indicated by level_idc[i] applies. Theapplicable_op_target_view_id[i][j][k] element may specify the k-thtarget output view for the j-th operation point to which the levelindicated by level_idc[i] applies. Theapplicable_op_num_views_minus1[i][j] element may specify the number ofviews, including the views that are dependent on the target output viewsbut that do not belong to the target output views, in the j-th operationpoint to which the level indicated by level_idc[i] applies.

Accordingly, in the SPS for MVC, the number of views that may be used toform reference picture List 0 and reference picture List 1 may besignaled for each view. In addition, the prediction relationship for ananchor picture, as signaled in the SPS for MVC, may be different fromthe prediction relationship for the non-anchor picture (signaled in theSPS of MVC) of the same view.

As described in greater detail below, video encoder 20 and video decoder30 may flexibly arrange temporal and view prediction references whenconstructing reference picture lists. Allowing flexible arrangementprovides not only potential coding efficiency gain, but also errorresilience, because reference picture section and redundant picturemechanisms may be extended to the view dimension. Video encoder 20and/or video decoder 30 may, in an example, construct a referencepicture list according to the following steps:

-   -   1) Initialize the reference picture list for temporal (i.e.,        intra-view) reference pictures, such that reference pictures        from other views are not considered.    -   2) Append the inter-view reference pictures to the end of the        list in the order in which the pictures occur in the MVC SPS        extension.    -   3) Apply a reference picture list reordering (RPLR) process for        both intra-view and inter-view reference pictures. Inter-view        reference pictures may be identified in the RPLR commands by        their index values as specified in the MVC SPS extension.

In MVC, video encoder 20 and/or video decoder 30 may, when decodingmultiview video data, activate zero or one picture parameter set (PPS)as an active PPS and zero or more view PPS (VPPS) as the active VPPS,where each active VPPS is active specifically for a particular vieworder index value less than a maximum view order index value. That is,video encoder 20 and/or video decoder 30 may activate a PPS that appliesto every view component of the multiview video data within an accessunit. Video encoder 20 and/or video decoder 30 may also activate a VPPSthat applies only to a subset of the view components in the access unit.In some instances, the VPPS may include one or more syntax elements thatoverride one or more syntax elements specified in the PPS for thoseviews for which the VPPS was activated. In some instances, the VPPS mayinclude one or more syntax elements that augment one or more syntaxelements specified in the PPS for those views for which the VPPS wasactivated.

Moreover, in MVC, video encoder 20 and/or video decoder 30 may, whendecoding multiview video data, activate zero or one MVC sequenceparameter set (SPS) as the active MVC SPS zero or more view SPS (VSPS)as the active VSPS, where each active VSPS is active specifically for aparticular view order index value less than a maximum view order indexvalue. That is, video encoder 20 and/or video decoder 30 may activate aSPS that applies to every view component of the multiview video datawithin one or more access units. Video encoder 20 and/or video decoder30 may also activate a VSPS that applies only to a subset of the viewcomponents in the one or more access units. In some instances, the VSPSmay include one or more syntax elements that override one or more syntaxelements specified in the SPS for those views for which the VSPS wasactivated. In some instances, the VSPS may include one or more syntaxelements that augment one or more syntax elements specified in the SPSfor those views for which the VSPS was activated.

Additionally, MVC provides functionality for parsing or extractingvarious so-called operation portions from a single bitstream. Eachoperation point may represent a different combination of views of themultiview video data encoded at varying temporal frame rates and spatialresolutions. In other words, an operation point may refer to an encodingof multiview video data in three dimensions including the view dimension(reflecting the number of views), the temporal dimensional (reflecting aframe rate) and spatial dimension (reflecting spatial resolution).

An operation point may be identified by a temporal_id value representingthe target temporal level and a set of view_id values representing thetarget output views. One operation point is associated with a bitstreamsubset, which consists of the target output views and all other viewsthe target output views depend on, that is derived using thesub-bitstream extraction process as specified in subclause H.8.5.3 ofthe three dimensional video coding (3DVC) extension of H.264/AVC withtIdTarget equal to the temporal_id value and viewIdTargetList consistingof the set of view_id values as inputs. More than one operation pointmay be associated with the same bitstream subset. When 3DVC states “anoperation point is decoded,” it refers to the decoding of a bitstreamsubset corresponding to the operation point and subsequent output of thetarget output views. In other words, each operation point is representedwith a number of views target for output in a certain temporal leveland/or spatial resolution or level.

In the sequence parameter set MVC extension, different operation pointsmay be signaled with level_idc values. The following syntax elements arenamed level definitions syntax elements.

num_level_values_signalled_minus1 0 ue(v) for( i = 0; i <=num_level_values_signalled_minus1; i++ ) { level_idc[ i ] 0 u(8)num_applicable_ops_minus1[ i ] 0 ue(v) for( j = 0; j <=num_applicable_ops_minus1[ i ]; j++ ) { applicable_op_temporal_id[ i ][j ] 0 u(3) applicable_op_num_target_views_minus1[ 0 ue(v) i ][ j ] for(k = 0; k <= applicable_op_num_target_views_minus1[ i ][ j ]; k++ )applicable_op_target_view_id[ i ][ j ][ 0 ue(v) k ]applicable_op_num_views_minus1[ i ][ j ] 0 ue(v) }

For each level_idc signaled in the MVC SPS extension, a newlevel_idc_depth is signaled in the 3D video (3DV) SPS extension. So ifit is assumed that all MVC operation points have the same level_idc[i],after including depth components and constructing 3DVC operation points,the 3DVC operation points will have the same level oflevel_idc_depth[i]. A detailed syntax design is shown as follows.

De- scrip- seq_parameter_set_3dvc_extension( ) { C tor . . . for( i = 0;i <= num_level_values_signalled_minus1; i++ ) level_idc_depth[ i ] 0u(8) . . . }

In addition, MVC provides that a view component may be removed from thedecoded picture buffer (DPB) if the view component is not further usedfor inter-view reference and the view component is not used for output,when decoding a view component in the same access unit as the viewcomponent to be removed.

Currently, 3DVC provides no way by which to distinguish between textureand depth components of a view component, where the term “viewcomponent” refers to a picture of a view specified by 3D multiview videodata. As a result, when encoding the texture and depth components of aview, the video encoder typically handles or otherwise processes boththe texture and depth components as view components in a manner similarto that described above with respect to MVC without providing any way bywhich to distinguish between texture and depth components. That is, 3DVCcurrently provides for handling or coding of view components withoutproviding a way by which to individually process texture componentsseparately from depth components. This lack of distinction in 3DVC mayresult in less coding efficiency and/or lower quality of reconstructedvideo data.

For example, a depth component may currently be required to be specifiedat the same resolution as a corresponding texture component so as toaccommodate joint handling of this view component. A higher resolutiondepth component (in comparison to the resolution of the texturecomponent) may, however, result in three dimensional (3D) video playbackin that a better, more immersive 3D video may result that better mimicswhat a viewer's visual system expects. Moreover, a lower resolutiondepth component (compared to the resolution of the texture component)may provide the same or similar immersive 3D experience in certaininstances but consume less bits when coded and thereby increase codingefficiency. By failing to enable separate handling of depth and texturecomponents, 3DVC may reduce coding efficiency and/or provide for lowerquality of reconstructed video data (often, in terms, of the viewingexperience).

The techniques of this disclosure generally relate to enabling separateor independent handling of texture components and depth components of aview when processing or coding 3D video data. For example, a sequenceparameter set (SPS) 3DVC extension can be added for the 3DVC relatedprofiles. Inside this SPS 3DVC extension, one or more of the followingmay be signaled: the picture size of the depth map sequences, the sizeof the picture to be displayed by the depth map sequences, and thelevels of the operation points with depth map pictures taken intoconsideration, where each of the specific level corresponds to a levelwhich has already been defined in the SPS MVC extension. The size of thepicture to be displayed may be a decoded picture outputted by a displaydevice.

In a 3DVC codec, a view component of each view of video data in aspecific time instance may include a texture view component and a depthview component. The texture view component may include luminance (Y)components and chrominance (Cb and Cr) components. Luminance(brightness) and chrominance (color) components are collectivelyreferred to herein as “texture” components. The depth view component maybe from a depth map of an image. In 3D image rendering, depth mapsinclude depth components and can be used for generating virtual viewsfrom a provided viewing perspective. Syntax elements for depthcomponents and texture components may be signaled with the coded blockunit. Coded block units, also referred to simply as “coded blocks” inthis disclosure, may correspond to macroblocks in ITU-T H.264/AVC(Advanced Video Coding).

This disclosure describes signaling techniques that may be applied by anencoder and used by a decoder during the inter-prediction stage of avideo encoding and/or decoding process. The described techniques arerelated to the coding of three-dimensional (“3D”) video content. The 3Dvideo content may be represented, for example, as multiview video plusdepth (“MVD”) coded blocks. More specifically, the techniques involvereceipt of at least one two-dimensional image having texture viewcomponents and depth view components. Some texture view components anddepth information may be coded together into a single coded block or asseparate blocks. An image may be broken into slices of images. Syntaxelements for coding texture view components and depth view componentsmay be signaled in a sequence parameter set. Depth view components mayor may not be predicted from the texture view components.

In the context of video coding standard, a “profile” corresponds to asubset of algorithms, features, or tools and constraints that apply tothem. As defined by the H.264 standard, for example, a “profile” is asubset of the entire bitstream syntax that is specified by the H.264standard. A “level” corresponds to the limitations of the decoderresource consumption, such as, for example, decoder memory andcomputation, which are related to the resolution of the pictures, bitrate, and macroblock (MB) processing rate. A profile may be signaledwith a profile_idc (profile indicator) value, while a level may besignaled with a level_idc (level indicator) value.

In the H.264/AVC standard, Network Abstraction Layer (NAL) units aredefined to provide a “network-friendly” video representation to addressapplications such as video telephony, storage, or streaming video. NALunits can be categorized to Video Coding Layer (VCL) NAL units andnon-VCL NAL units. VCL units may contain a core compression engine andcomprise block, macroblock (MB), and slice levels. Other NAL units arenon-VCL NAL units.

For 2D video encoding, each NAL unit may contain a one byte NAL unitheader and a payload of varying size. Five bits may be used to specifythe NAL unit type. Three bits may be used for nal_ref_idc, whichindicates how important the NAL unit is in terms of being referenced byother pictures (NAL units). For example, setting nal_ref_idc equal to 0means that the NAL unit is not used for inter prediction. As H.264/AVCmay be expanded to include 3D video encoding, such as the scalable videocoding (SVC) standard, the NAL header may be similar to that of the 2Dscenario. For example, one or more bits in the NAL unit header may beused to identify that the NAL unit is a four-component NAL unit.

NAL unit headers may also be used for MVC NAL units. However, in MVC,the NAL unit header structure may be retained except for prefix NALunits and MVC coded slice NAL units. Techniques of the presentdisclosure provide a different NAL unit type that may be used to signala super SPS.

The following table provides one example of a sequence parameter setRBSP syntax, in accordance with one aspect of the present disclosure.For illustrative purposes only, for examples associated with this table,it may be assumed that the texture and depth have the same view_id valueand the nal_unit_type is used to distinguish the texture and depth.Below, the bolded items represent items that have been added, updated oraltered in accordance with examples of this disclosure, in comparison tocurrent or previous versions of the working draft for the 3DVC extensionto MVC. Moreover, reference to annexes, such as annex G in the tablebelow, refer to annexes of the H.264 video coding standard.

subset_seq_parameter_set_rbsp( ) { C Descriptor seq_parameter_set_data() 0 if( profile_idc = = 83 | | profile_idc = = 86 ) {seq_parameter_set_svc_extension( ) /* specified in Annex G 0 */svc_vui_parameters_present_flag 0 u(1) if(svc_vui_parameters_present_flag = = 1 ) svc_vui_parameters_extension( )/* specified in Annex G 0 */ } else if( profile_idc = = 118 | |profile_idc = = 128 ) { bit_equal_to_one /* equal to 1 */ 0 f(1)seq_parameter_set_mvc_extension( ) /* specified in 0 Annex H */mvc_vui_parameters_present_flag 0 u(1) if(mvc_vui_parameters_present_flag = = 1 ) mvc_vui_parameters_extension( )/* specified in Annex H 0 */ } else if ( profile_idc = = 138 | |profile_idc = = 148 ) { //138: 3DV base profile; 148: 3DV Asymmetricprofile bit_equal_to_one /* equal to 1 */ 0 f(1)seq_parameter_set_mvc_extension( ) seq_parameter_set_3dvc_extension( )3dvc_vui_parameter_present_flag 0 u(1) if(3dvc_vui_parameter_present_flag ) { 3dvc_vui_parameters_extension( ) /*specified in Annex I */ } } additional_extension3_flag 0 u(1) if (additional_extension3_flag ) while( more_rbsp_data( ) )additional_extension3_data_flag 0 u(1) } rbsp_trailing_bits( ) 0 }

According to table shown above, 3dvc_vui_parameter_present_flag equal to1 indicates that 3dvc_vui_parameters_extension( ) is present. When3dvc_vui_parameter_present_flag equals 0, the flag indicates that3dvc_vui_parameters_extension( ) is not present. For example,3dvc_vui_parameter_present_flag indicates that an extensionincorporating some of the techniques of this disclosure is present in asequence parameter set.

In some examples, a subset SPS with MVC profiles (e.g., stereo high ormultiview high) may have the same SPS id as that of the subset SPS with3DV profiles, so that the texture view components will refer to a sameSPS_id having different content in different profiles. For example, asubset SPS with MVC may correspond to an operation point that only hastexture. Having the same SPS id as that of a subset SPS with 3DVprofiles may enable an operation point that only included texture to beextracted by a decoder or network device, such as a media aware networkelement (MANE).

Multiview High Profile supports an arbitrary number of views. StereoHigh Profile supports two-view stereoscopic video. In other examples,the techniques described herein may apply to examples using other MVCprofiles.

The following table provides an example of extension syntax elements forthe sequence parameter set 3DVC extension.

De- scrip- seq_parameter_set_3dvc_extension( ) { C tordisable_depth_inter_view_flag 0 u(1) depth_pic_width_in_mbs_minus1 0ue(v) depth_pic_height_in_map_units_minus1 0 ue(v)depth_frame_cropping_flag 0 u(1) if( depth_frame_cropping_flag ) {depth_frame_crop_left_offset 0 ue(v) depth_frame_crop_right_offset 0ue(v) depth_frame_crop_top_offset 0 ue(v) depth_frame_crop_bottom_offset0 ue(v) } for( i = 0; i <= num_level_values_signalled_minus1; i++ )level_idc_depth[ i ] 0 u(8) }

In one example, the sequence parameter set 3DVC extension specifiesinter-view dependency relationships of the additional views with ahigher resolution than the other views in the coded video sequence. Thetexture view components of the other views, with a lower resolutionbelong to a sub-bitstream that conforms to Annex H. The sequenceparameter set 3DVC extension also specifies the dependency of the depthview components. The higher resolution views can have double width,identical height or double height, or identical width of the otherviews. In some examples, the higher resolution views can have onlydouble width, identical height or double height, or identical width ofthe other views.

A chroma_format_idc for depth view components is inferred to be equal to4:0:0.

The syntax element disable_depth_inter_view_flag may have the samesemantics as in the flag with the same name in m22583. The syntaxelement depth_pic_width_in_mbs_minus1 plus 1 specifies the width of eachdepth view component picture in units of macroblocks. A variable for thepicture width of depth view components in units of macroblocks may bederived as:

PicWidthInMbs=pic_width_in_mbs_minus1+1  (1)

A variable for picture width of depth view components for a lumacomponent is derived as:

PicWidthInSamplesL=PicWidthInMbs*16  (2)

In some examples, the syntax elementdepth_pic_height_in_map_units_minus1 plus 1 specifies the height inslice group map units of a decoded frame of depth view components. Thevariables PicHeightInMapUnits and PicSizeInMapUnits are derived as:

PicHeightInMapUnits=pic_height_in_map_units_minus1+1  (3)

PicSizeInMapUnits=PicWidthInMbs*PicHeightInMapUnits  (4)

In some examples, when the syntax element depth_frame_cropping_flag isequal to 1, depth_frame_cropping_flag specifies that the frame croppingoffset parameters follow next in the sequence parameter set for depthview components. depth_frame_cropping_flag equal to 0 specifies that theframe cropping offset parameters are not present for depth viewcomponents.

The syntax elements depth_frame_crop_left_offset,depth_frame_crop_right_offset, depth_frame_crop_top_offset, anddepth_frame_crop_bottom_offset may specify the samples of the picturesof the depth view components in the coded video sequence that are outputfrom the decoding process, in terms of a rectangular region specified inframe coordinates for output. These offsets may define a cropping windowfor the pictures of the decoded depth view components.

In some examples, the syntax element level_idc_depth[i] specifies thei-th level value signaled for the coded video sequence with depth viewcomponents.

It is possible to extract one or more views from an MVC bitstream toproduce a sub-bitstream. A sub-bitstream with a given reasonable set oftarget output views is referred to as an operation point. Because ofview dependencies, the set of target output views can be a subset of theviews contained in a sub-bitstream. The target output views can also beidentical to the views contained in the sub-bitstream. However, if aservice provider does not intend to support an operation point with alarge number of views, the number of target output views can be a subsetof the contained views. Note that the contained views are the views tobe decoded.

An operation point is identified by a temporal_id value representing atarget temporal level and a set of view_id values representing thetarget output views. One operation point is associated with a bitstreamsubset, which consists of the target output views and all other viewsthe target output views depend on, that is derived using thesub-bitstream extraction process as specified in sub-clause H.8.5.3 withtIdTarget equal to the temporal_id value and viewIdTargetList consistingof the set of view_id values as inputs. More than one operation pointmay be associated with the same bitstream subset. When the 3DVC states“an operation point is decoded,” it refers to the decoding of abitstream subset corresponding to the operation point and subsequentoutput of the target output views.

According to techniques described herein, the construction of theoperation points for 3DVC SPS extension may be the same as those in theMVC SPS extension, except that the depth view components are associated.In other words, for each operation point signaled in the MVC SPSextension having level equal to level_idc[i], a corresponding operationpoint is enabled in 3DVC SPS extension, with the same collection oftarget output views and temporal_id value, but further include, for eachview component that includes a depth component, a level oflevel_idc_depth[i].

Alternatively, the level_idc values signaled in the SPS MVC extension ofthe current SPS with a 3DV profile, are always for operation pointscontaining depth NAL units, thus the syntax element level_idc_depth[i]is not signaled in some instances for 3DVC. For example, when signalinglevel_idc values in the SPS with a 3DV profile including the SPS MVCextension, according to techniques described herein, the syntax elementlevel_idc_depth[i] is not signaled because the level_idc values are foroperation points that contain depth NAL units.

The following table provides example semantics for a 3DVC VideoUsability Information (VUI) parameters extension.

3dvc_vui_parameters_extension( ) { C Descriptor vui_mvc_num_ops_minus1 0ue(v) for( i = 0; i <= vui_mvc_num_ops_minus1; i++ ) {vui_mvc_temporal_id[ i ] 0 u(3) vui_mvc_num_target_output_views_minus1[i ] 5 ue(v) depth_present_flag[ i ] 0 u(1) for( j = 0; j <=vui_mvc_num_target_output_views_minus1[ i ]; j++ ) vui_mvc_view_id[ i ][j ] 5 ue(v) vui_mvc_timing_info_present_flag[ i ] 0 u(1) if(vui_mvc_timing_info_present_flag[ i ] ) { vui_mvc_num_units_in_tick[ i ]0 u(32) vui_mvc_time_scale[ i ] 0 u(32) vui_mvc_fixed_frame_rate_flag[ i] 0 u(1) } vui_mvc_nal_hrd_parameters_present_flag[ i ] 0 u(1) if(vui_mvc_nal_hrd_parameters_present_flag[ i ] ) hrd_parameters( ) 0vui_mvc_vcl_hrd_parameters_present_flag[ i ] 0 u(1) if(vui_mvc_vcl_hrd_parameters_present_flag[ i ] ) hrd_parameters( ) 0 if(vui_mvc_nal_hrd_parameters_present_flag[ i ] | |vui_mvc_vcl_hrd_parameters_present_flag[ i ] )vui_mvc_low_delay_hrd_flag[ i ] 0 u(1) vui_mvc_pic_struct_present_flag[i ] 0 u(1) } }In the example table shown directly above, depth_present_flag[i] equalto 1 indicates that the current operation point includes depth viewcomponent for each view. depth_present_flag[i] equal to 0 indicates thatthe current operation point does not include any depth view component.

Other syntax elements may have the same semantics as those in the MVCVUI parameters extension with the same names.

Alternatively, depth_present_idc[i] may be signaled. The elementdepth_present_idc[i] equal to 1 may indicate that a current operationpoint includes depth view component for each view. In some examples,setting depth_present_idc[i] equal to 0 or 2 may indicate that thecurrent operation point includes only texture view components. In otherexamples, setting depth_present_idc[i] equal to 0 may indicate that thecurrent operation point does not include any depth view component. Inother examples, setting depth_present_idc[i] equal to 2 may indicatethat the current operation point does not include any depth viewcomponent.

In another example, a depth view component and a texture view component,even belonging to the same view, may have different view_id valuessignaled. However, the depth view components may still share the sameview dependency as the texture. In some examples, the SPS 3DVC extensioncontains a mapping of the view_id values.

The following table provides another example of a SPS 3DVC extension.

De- scrip- seq_parameter_set_3dvc_extension( ) { C tor for ( i = 0; i <=num_views_minus1 ; i++) view_id_depth[ i ] 0 ue(v)disable_depth_inter_view_flag 0 u(1) depth_pic_width_in_mbs_minus1 0ue(v) depth_pic_height_in_map_units_minus1 0 ue(v)depth_frame_cropping_flag 0 u(1) if( depth_frame_cropping_flag ) {depth_frame_crop_left_offset 0 ue(v) depth_frame_crop_right_offset 0ue(v) depth_frame_crop_top_offset 0 ue(v) depth_frame_crop_bottom_offset0 ue(v) } for( i = 0; i <= num_level_values_signalled_minus1; i++ )level_idc_depth[ i ] 0 u(8) }

The syntax element view_id_depth[i] specifies the view_id of the depthview with VOIdx equal to i, it belongs to the view with texture viewhaving a view_id equal to view_id[i].

In another example, keeping all other aspects the same, thelevel_idc_depth values can be signaled in the same way as the level_idcvalues signaled in the SPS MVC extension.

In another example, the depth view components may share a differentseq_parameter_set_data( ). As such, a width and height of the depth viewcomponents are signaled. In one example, the seq_parameter_set_data( )syntax may include chorma_format_idc, which may be 4:0:0 in someexamples. In these examples, the depth view prediction relation maystill share the same prediction relation as the texture view predictionrelation.

The following table provides an example of syntax elements for a subsetsequence parameter set RBSP syntax for when the depth view componentsshare the same seq_parameter_set_data( ) in accordance with one aspectof the present disclosure.

subset_seq_parameter_set_rbsp( ) { C Descriptor seq_parameter_set_data() 0 if( profile_idc = = 83 | | profile_idc = = 86 ) {seq_parameter_set_svc_extension( ) /* specified in 0 Annex G */svc_vui_parameters_present_flag 0 u(1) if(svc_vui_parameters_present_flag = = 1 ) svc_vui_parameters_extension( )/* specified in 0 Annex G */ } else if( profile_idc = = 118 | |profile_idc = = 128 ) { bit_equal_to_one /* equal to 1 */ 0 f(1)seq_parameter_set_mvc_extension( ) /* specified in 0 Annex H */mvc_vui_parameters_present_flag 0 u(1) if(mvc_vui_parameters_present_flag = = 1 ) mvc_vui_parameters_extension( )/* specified in 0 Annex H */ } else if ( profile_idc = = 138 | |profile_idc = = 148 ) { //138: 3DV base profile; 148: 3DV Asymmetricprofile bit_equal_to_one /* equal to 1 */ 0 f(1) seq_parameter_set_data() seq_parameter_set_mvc_extension( ) seq_parameter_set_3dvc_extension( )3dvc_vui_parameter_present_flag 0 u(1) if (3dvc_vui_parameter_present_flag ) { 3dvc_vui_parameters_extension( ) /*specified in Annex I */ } } additional_extension3_flag 0 u(1) if (additional_extension3_flag ) while( more_rbsp_data( ) )additional_extension3_data_flag 0 u(1) } rbsp_trailing_bits( ) 0 }

The following table provides an example sequence parameter set 3dVCextension syntax for when the depth view components share the sameseq_parameter_set_data( ) in accordance with one aspect of the presentdisclosure.

De- scrip- seq_parameter_set_3dvc_extension( ) { C tordisable_depth_inter_view_flag 0 u(1) for( i = 0; i <=num_level_values_signalled_minus1; i++ ) level_idc_depth[ i ] 0 u(8) }

In some examples, the semantics of some of the syntax elements shown insome of the foregoing tables may be similar or the same as the analogoussyntax elements described with respect to other ones of these tables.

In another example, a new NAL unit type may be provided. The NAL unittype may have a value, such as 15, that is used to signal a super SPSfor the 3DV profile. The next three tables may correspond to syntaxelements for a super SPS for the 3DV profile. In some examples, a superSPS may signal both depth view components and texture components.

The following table provides one example of a super sequence parameterset RBSP syntax. The SPS 3DVC extension syntax of the following tablemay be signaled using the new NAL unit type.

supset_seq_parameter_set_rbsp( ) { C Descriptor seq_parameter_set_data() 0 if ( profile_idc = = 138) { //138: 3DV base profile;bit_equal_to_one /* equal to 1 */ 0 f(1)seq_parameter_set_mvc_extension( ) seq_parameter_set_3dvc_extension( )3dvc_vui_parameter_present_flag 0 u(1) if (3dvc_vui_parameter_present_flag ) { 3dvc_vui_parameters_extension( ) /*specified in Annex I */ } } additional_extension1_flag 0 u(1) if (additional_extension1_flag ) while( more_rbsp_data( ) )additional_extension1_data_flag 0 u(1) } rbsp_trailing_bits( ) 0 }

The following table provides one example of a SPS 3DVC extension syntax,according to techniques described herein. The SPS 3DVC extension syntaxof the following table may be signaled using the new NAL unit type.

seq_parameter_set_3dvc_extension( ) { C Descriptordisable_depth_inter_view_flag 0 u(1) cam_paras( ) depth_range( ) }

The following table provides one example of a 3DVC VUI parametersextension syntax, according to techniques described herein. The 3DVC VUIparameters extension syntax of the following table may be signaled usingthe new NAL unit type.

3dvc_vui_parameters_extension( ) { C Descriptor vui_mvc_num_ops_minus1 0ue(v) for( i = 0; i <= vui_mvc_num_ops_minus1; i++ ) {vui_mvc_temporal_id[ i ] 0 u(3) vui_mvc_num_target_output_views_minus1[i ] 5 ue(v) depth_present_flag[ i ] 0 u(1) for( j = 0; j <=vui_mvc_num_target_output_views_minus1[ i ]; j++ ) vui_mvc_view_id[ i ][j ] 5 ue(v) vui_mvc_timing_info_present_flag[ i ] 0 u(1) if(vui_mvc_timing_info_present_flag[ i ] ) { vui_mvc_num_units_in_tick[ i ]0 u(32) vui_mvc_time_scale[ i ] 0 u(32) vui_mvc_fixed_frame_rate_flag[ i] 0 u(1) } vui_mvc_nal_hrd_parameters_present_flag[ i ] 0 u(1) if(vui_mvc_nal_hrd_parameters_present_flag[ i ] ) hrd_parameters( ) 0vui_mvc_vcl_hrd_parameters_present_flag[ i ] 0 u(1) if(vui_mvc_vcl_hrd_parameters_present_flag[ i ] ) hrd_parameters( ) 0 if(vui_mvc_nal_hrd_parameters_present_flag[ i ] | |vui_mvc_vcl_hrd_parameters_present_flag[ i ] )vui_mvc_low_delay_hrd_flag[ i ] 0 u(1) vui_mvc_pic_struct_present_flag[i ] 0 u(1) } }

In some examples, the semantics of some of the syntax elements shown inthe foregoing tables may be similar or the same as the analogous syntaxelements described with respect to other ones of the foregoing tables.The levels defined in the MVC SPS extension may apply to the operationpoints, taking depth NAL units into consideration. In the 3DV relatedprofile, one SPS, one subset SPS, and one superset SPS can besimultaneously activated.

As a result, MVC may be extended by way of 3DVC to provide for separatehandling of depth and texture components. By enabling such independenthandling, the various aspects of the techniques described in thisdisclosure may promote bit savings (or, in other words, more efficientcoding of multiview video data) and/or better quality of reconstructedvideo data (which again may be measured in terms of a perceived viewingexperience).

For example, various aspects of the techniques described in thisdisclosure may enable a video coding device (which may represent a termused in this disclosure to refer to any device that includes a videoencoder and/or a video decoder, such as source device 12 and/ordestination device 14) to activate a parameter set as a textureparameter set for the texture component of the view component based atleast on a view order index value assigned to the view component of themultiview video data. The view order index may describe the decodingorder of a corresponding view component of an access unit. The vieworder index can be used with a picture order count (POC) value or aframe value to identify a view component of a bitstream. This aspect ofthe techniques may therefore provide for a parameter set, such as a PPSor SPS, that is activated only for the texture component of a viewcomponent and does not apply to the corresponding depth component of thesame view component. In this respect, the video coding device may codeonly the texture component of the view component and not the depthcomponent of the view component based on the activated texture parameterset.

Additionally, the video coding device may activate a parameter set forthe depth component of the view component based at least on the vieworder index value assigned to the view component of the multiview videodata. That is, in some instances, the video coding device may activate atexture-specific parameter set for the texture component of a viewcomponent and then activate yet another parameter set specifically forthe depth component of the same view component. As a result, the videocoding device may code the depth component of the view component basedon the parameter set activated for the depth component of the viewcomponent and not the activated texture parameter set. The video codingdevice may code the texture component based on the activated textureparameter set. In this way, the techniques may promote separateactivation of parameter sets, such as a PPS or SPS, for texture anddepth components of a view component, providing a way by which tofacilitate separate handling or processing of depth and texturecomponents in an MVC-compatible 3DVC view.

Various aspects of the techniques described in this disclosure may alsopromote separate handling of depth and texture components by enabling avideo coding device to determine a nested supplemental information (SEI)message that applies to both texture and depth components of a viewcomponent or only to a depth component of the view component. The term“nested SEI message” refers to an SEI message that incorporates variousportions of another SEI message such that a nested SEI message iseffectively “nested” within the scope of another SEI message. Byenabling a nested SEI message to apply only to a depth component, theseaspects of the techniques may again promote separate handling of textureand depth components.

A video coding device (i.e., source device 12 and/or destination device14 in the example of FIG. 1) may perform these aspects of the techniquesto determine a supplemental enhancement information message that appliesto coding of the view component of the multiview video data. This SEImessage may be referred to as a parent SEI message to reflect that itapplies for a particular view component and sets the scope for anynested SEI messages. The video coding device may then determine a nestedsupplemental enhancement information message that applies in addition tothe supplemental enhancement information message when coding the depthcomponent of the view component. This nested SEI message may identifythe parent SEI message and indicate that this nested SEI message onlyapplies to the depth component of the view component to which the parentSEI message applies. The video coding device may then process the depthcomponent of the view component based on the supplemental enhancementinformation message and the nested supplemental enhancement informationmessage.

Typically, the nested SEI message includes a flag or other identifierthat indicates whether the nested SEI message applies to both thetexture and depth components of the view component or only to the depthcomponent. Thus, in some instances, the video coding device maydetermine that the nested supplemental enhancement information messageapplies in addition to the supplemental enhancement information messagewhen only processing the depth component of the view component andprocesses only the depth component of the view component and not thetexture component of the view component based on the supplementalenhancement information message and the nested supplemental enhancementinformation message. Alternatively, the video coding device maydetermine that the nested supplemental enhancement information messageapplies in addition to the supplemental enhancement information messagewhen processes the texture component of the view component and processesthe texture component of the view component based on the supplementalenhancement information message and the nested supplemental enhancementinformation message. Again, these aspects of the techniques againfacilitate separate handling or processing of depth and texturecomponents of the view component.

Other aspects of the techniques described in this disclosure may promoteseparate handling of depth and texture components by enabling a videocoding device to separately remove texture and depth components from adecoded picture buffer. The decoded picture buffer refers to a memory orother computer-readable medium capable of storing reference pictures foruse in coding a current view component. Because the techniques set forthin this disclosure enable separate handling of texture and depthcomponents, a video coding device may code a texture component of a viewcomponent using reference pictures different than those used when codinga depth component of the same view component contrary to conventionalMVC where a view component (and therefore the depth and texturecomponents of that view component) was coded using the same referencepictures. As a result, there may be instances where depth components ofa reference view component may be removed from the decoded picturebuffer prior to texture components of the same reference view component,and a texture component of a reference view component may be removedfrom the decoded picture buffer prior to the depth component of the samereference view component.

In operation, a video coding device may perform the techniques describedin this disclosure by storing a depth component in a decoded picturebuffer and analyzing a view dependency to determine whether the depthcomponent is used for inter-view prediction. The video coding device maythen remove the depth component from the decoded picture buffer inresponse to determining that the depth component is not used forinter-view prediction. That is, the video coding device may remove thedepth component of a reference view component from the decoded picturebuffer without removing the texture component of the same reference viewcomponent in response to determining that the depth component is notused for inter-view prediction. The video coding device may, prior toremoving the depth component, validate this depth component as beingeligible for removal by determining that the depth component does notbelong to a target output view and that the depth component isassociated with a network abstraction layer reference identificationcode having a value equal to zero (meaning that the content of the NALunit encapsulating the depth component is not used to constructreference pictures for inter-picture prediction).

Additional aspects of the techniques described in this disclosure mayalso permit or otherwise facilitate separate handling of depth andtexture components. For example, in terms of operation points, thetechniques may enable a video coding device to generate a SEI messagethat includes a first syntax element, a second syntax element, and athird syntax element, where the first syntax element indicates whetheran operation point contains a depth component. When the operation pointcontains a depth component, the video coding device may define thesecond syntax element to indicate a number of depth components on whicha target output view of the operation point directly depends and definethe third syntax elements to identify the depth components on which thetarget output view of the operation point directly depends.

In some instances, the operation points may include a first subset ofthe operation points and a second subset of the operation points, whereeach operation point in the first subset contains only a texturecomponent and each operation point in the second subset contains a depthcomponent. The video coding device may then determine that a profileidentifier is equal to a given value that is associated with 3D videocoding and generate, in response to determining that the profileidentifier is equal to the given value, a subset SPS such that thesubset SPS includes a first SPS extension and a second SPS extension.The first SPS extension may indicate the first subset and the levels towhich the operation points in the first subset belong. The second SPSextension may indicate the second subset and the levels to whichoperation points in the second subset belong. In this way, thetechniques may permit operations points to be defined separately fortexture and depth components and by level.

This aspect of the techniques may leverage the separate handling ofdepth and texture components to permit operation points to be moreeasily extracted from a bitstream for multiview video coding. Bysignaling whether an operation point includes depth, a video decoder,such as video decoder 30, may determine which operation point bestaccommodates the abilities of video decoder 30. For example, videodecoder 30 may be optimized to perform multiview video coding usingviews that do not include depth, preferring multiview video data whereboth the left and right eye perspectives are provided as separatepictures. Video decoder 30 may alternatively be optimized fordepth-based multiview video data but may only accommodate a single viewrather than two or more views. By signaling when the encoded multiviewvideo data includes depth, and when including depth, the number of depthcomponents on which the target output views of the operation pointdirectly depends, video decoder 30 may select an operation point thataccommodates the capabilities or optimizations of video decoder 30.

Additionally, a video coding device may perform aspects of thetechniques described in this disclosure to signal levels to whichoperation points belong, where at least some of the operation pointscontaining depth components. The video coding device may then determinethat a profile identifier is equal to a given value that is associatedwith 3D video coding and generate, in response to determining that theprofile identifier is equal to the given value, a subset SPS such thatthe subset SPS includes a MVC SPS extension that signals the operationpoints and the levels to which the operation points belong. Each of theoperation points, in this example, may specify one or more output views,where each of the output views contains both a texture component and adepth component.

In yet other instances, the video coding device may perform thetechniques described in this disclosure to generate, in a SPS, a syntaxelement that indicates a number of views to be decoded for an operationpoint in an MVC process, where each of the views has one of a number oftexture components and one of a number of depth components. The videocoding device may then signal, in the SPS, the number of texturecomponents to be decoded for the operation point and the number of depthcomponents to be decoded for the operation point. Again, by virtue offacilitating separate handling of depth and texture components, thetechniques may provide for signaling of how these depth and texturecomponents are utilized to form operation points.

FIG. 2 is a block diagram illustrating an example video encoder 20 thatmay implement the techniques described in this disclosure for codingmultiview video data. Video encoder 20 receives video data to beencoded. In the example of FIG. 2, video encoder 20 includes a modeselect unit 40, summer 50, transform processing unit 52, quantizationunit 54, entropy encoding unit 56, and reference picture memory 64. Modeselect unit 40, in turn, includes motion/disparity estimation unit 42,motion compensation unit 44, intra prediction unit 46, and partitionunit 48.

For video block reconstruction, video encoder 20 also includes inversequantization unit 58, inverse transform processing unit 60, and summer62. A deblocking filter (not shown in FIG. 2) may also be included tofilter block boundaries to remove blockiness artifacts fromreconstructed video. If desired, the deblocking filter would typicallyfilter the output of summer 62. Additional loop filters (in loop or postloop) may also be used in addition to the deblocking filter. Suchfilters are not shown for brevity, but if desired, may filter the outputof summer 50 (as an in-loop filter).

Mode select unit 40 may receive raw video data in the form of blocksfrom one or more views. Mode select unit 40 may select one of the codingmodes, intra or inter, e.g., based on error results, and provides theresulting intra- or inter-coded block to summer 50 to generate residualblock data and to summer 62 to reconstruct the encoded block for use asa reference picture. Mode select unit 40 also provides syntax elements,such as motion vectors, intra-mode indicators, partition information,and other such syntax information, to entropy encoding unit 56.

Motion/disparity estimation unit 42 and motion compensation unit 44 maybe highly integrated, but are illustrated separately for conceptualpurposes. Motion estimation, performed by motion/disparity estimationunit 42, is the process of generating motion vectors, which estimatemotion for video blocks. A motion vector, for example, may indicate thedisplacement of a PU of a video block within a current picture relativeto a predictive block within a reference picture (or other coded unit)relative to the current block being coded within the current picture (orother coded unit).

A predictive block is a block that is found to closely match the blockto be coded, in terms of pixel difference, which may be determined bysum of absolute difference (SAD), sum of square difference (SSD), orother difference metrics. In some examples, video encoder 20 maycalculate values for sub-integer pixel positions of reference picturesstored in reference picture memory 64, which may also be referred to asa reference picture buffer. For example, video encoder 20 mayinterpolate values of one-quarter pixel positions, one-eighth pixelpositions, or other fractional pixel positions of the reference picture.Therefore, motion/disparity estimation unit 42 may perform a motionsearch relative to the full pixel positions and fractional pixelpositions and output a motion vector with fractional pixel precision.

Motion/disparity estimation unit 42 calculates a motion vectors for a PUof a video block in an inter-coded slice by comparing the position ofthe PU to the position of a predictive block of a reference picture.Motion estimation/disparity unit 42 may also be configured to performinter-view prediction, in which case motion estimation/disparity unit 42may calculate displacement vectors between blocks of one view picture(e.g., view 0) and corresponding blocks of a reference view picture(e.g., view 1). In general, data for a motion/disparity vector mayinclude a reference picture list, an index into the reference picturelist (ref_idx), a horizontal component, and a vertical component. Thereference picture may be selected from a first reference picture list(List 0), a second reference picture list (List 1), or a combinedreference picture list (List C), each of which identify one or morereference pictures stored in reference picture memory 64. With respectto the combined list, video encoder 20 alternately select entries fromtwo lists (i.e., List 0 and List 1) to be inserted (appended) into thecombined list. When an entry is already put in the combined list, bychecking the POC number, video encoder 20 may not insert the entryagain. For each list (i.e., List 0 or List 1), video encoder 20 mayselect the entries based on ascending order of the reference index.

Motion/disparity estimation unit 42 may generate and send amotion/disparity vector that identifies the predictive block of thereference picture to entropy encoding unit 56 and motion compensationunit 44. That is, motion/disparity estimation unit 42 may generate andsend motion vector data that identifies the reference picture listcontaining the predictive block, an index into the reference picturelist identifying the picture of the predictive block, and a horizontaland vertical component to locate the predictive block within theidentified picture.

Motion compensation, performed by motion compensation unit 44, mayinvolve fetching or generating the predictive block based on themotion/disparity vector determined by motion/disparity estimation unit42. Again, motion/disparity estimation unit 42 and motion compensationunit 44 may be functionally integrated, in some examples. Upon receivingthe motion vector for the PU of the current video block, motioncompensation unit 44 may locate the predictive block to which the motionvector points in one of the reference picture lists.

Summer 50 forms a residual video block by subtracting pixel values ofthe predictive block from the pixel values of the current video blockbeing coded, forming pixel difference values, as discussed below. Ingeneral, motion/disparity estimation unit 42 performs motion estimationrelative to luma components, and motion compensation unit 44 uses motionvectors calculated based on the luma components for both chromacomponents and luma components. Mode select unit 40 may also generatesyntax elements associated with the video blocks and the video slice foruse by video decoder 30 in decoding the video blocks of the video slice.

Intra-prediction unit 46 may intra-predict a current block, as analternative to the inter-prediction performed by motion/disparityestimation unit 42 and motion compensation unit 44, as described above.In particular, intra-prediction unit 46 may determine anintra-prediction mode to use to encode a current block. In someexamples, intra-prediction unit 46 may encode a current block usingvarious intra-prediction modes, e.g., during separate encoding passes,and intra-prediction unit 46 (or mode select unit 40, in some examples)may select an appropriate intra-prediction mode to use from the testedmodes.

For example, intra-prediction unit 46 may calculate rate-distortionvalues using a rate-distortion analysis for the various testedintra-prediction modes, and select the intra-prediction mode having thebest rate-distortion characteristics among the tested modes.Rate-distortion analysis generally determines an amount of distortion(or error) between an encoded block and an original, unencoded blockthat was encoded to produce the encoded block, as well as a bitrate(that is, a number of bits) used to produce the encoded block.Intra-prediction unit 46 may calculate ratios from the distortions andrates for the various encoded blocks to determine which intra-predictionmode exhibits the best rate-distortion value for the block.

After selecting an intra-prediction mode for a block, intra-predictionunit 46 may provide information indicative of the selectedintra-prediction mode for the block to entropy encoding unit 56. Entropyencoding unit 56 may encode the information indicating the selectedintra-prediction mode. Video encoder 20 may include in the transmittedbitstream configuration data, which may include a plurality ofintra-prediction mode index tables and a plurality of modifiedintra-prediction mode index tables (also referred to as codeword mappingtables), definitions of encoding contexts for various blocks, andindications of a most probable intra-prediction mode, anintra-prediction mode index table, and a modified intra-prediction modeindex table to use for each of the contexts.

Video encoder 20 forms a residual video block by subtracting theprediction data from mode select unit 40 from the original video blockbeing coded. Summer 50 represents the component or components thatperform this subtraction operation. Transform processing unit 52 appliesa transform, such as a discrete cosine transform (DCT) or a conceptuallysimilar transform, to the residual block, producing a video blockcomprising residual transform coefficient values. Transform processingunit 52 may perform other transforms which are conceptually similar toDCT. Wavelet transforms, integer transforms, sub-band transforms orother types of transforms could also be used. In any case, transformprocessing unit 52 applies the transform to the residual block,producing a block of residual transform coefficients. The transform mayconvert the residual information from a pixel value domain to atransform domain, such as a frequency domain.

Transform processing unit 52 may send the resulting transformcoefficients to quantization unit 54. Quantization unit 54 quantizes thetransform coefficients to further reduce bit rate. The quantizationprocess may reduce the bit depth associated with some or all of thecoefficients. The degree of quantization may be modified by adjusting aquantization parameter. In some examples, quantization unit 54 may thenperform a scan of the matrix including the quantized transformcoefficients. Alternatively, entropy encoding unit 56 may perform thescan.

Following quantization, entropy encoding unit 56 entropy codes thequantized transform coefficients. For example, entropy encoding unit 56may perform context adaptive variable length coding (CAVLC), contextadaptive binary arithmetic coding (CABAC), syntax-based context-adaptivebinary arithmetic coding (SBAC), probability interval partitioningentropy (PIPE) coding or another entropy coding technique. In the caseof context-based entropy coding, context may be based on neighboringblocks. Following the entropy coding by entropy encoding unit 56, theencoded bitstream may be transmitted to another device (e.g., videodecoder 30) or archived for later transmission or retrieval.

Inverse quantization unit 58 and inverse transform processing unit 60apply inverse quantization and inverse transformation, respectively, toreconstruct the residual block in the pixel domain, e.g., for later useas a reference block. Motion compensation unit 44 may calculate areference block by adding the residual block to a predictive block ofone of the pictures of reference picture memory 64. Motion compensationunit 44 may also apply one or more interpolation filters to thereconstructed residual block to calculate sub-integer pixel values foruse in motion estimation. Summer 62 adds the reconstructed residualblock to the motion compensated prediction block produced by motioncompensation unit 44 to produce a reconstructed video block for storagein reference picture memory 64. The reconstructed video block may beused by motion/disparity estimation unit 42 and motion compensation unit44 as a reference block to inter-code a block in a subsequent picture.

Video encoder 20 may generate a number of syntax elements, as describedabove, which may be encoded by entropy encoding unit 56 or anotherencoding unit of video encoder 20. In some examples, video encoder 20may generate and encode syntax elements for a 3DVC bitstream, asdescribed above, where again this 3DVC bitstream may be backwardscompatible with MVC. That is, a video decoder that supports MVC but thatdoes not support 3DVC may still decode the 3DVC bitstream encoded inaccordance with the techniques described in this disclosure.[explain/illustrate?]

Video encoder 20 may activate a parameter set as a texture parameter setfor the texture component of the view component based at least on a vieworder index value assigned to the view component of the multiview videodata. In other words, video encoder 20 may activate a parameter set,such as a PPS or SPS, only for the texture component of a view componentsuch that this texture parameter set does not apply to the correspondingdepth component of the same view component. In this respect, videoencoder 20 may encode only the texture component of the view componentand not the depth component of the view component based on the activatedtexture parameter set.

In particular, mode select unit 40 of video encoder 20 may activate aparameter set by selecting a mode, e.g., intra-view prediction (whichmay involve temporal or inter-picture prediction where the pictures allcorrespond to the same view), inter-view prediction or intra-prediction.Mode select unit 40 may analyze each of the iterations of coding apicture, where each iteration may involve different parameters. Whenselecting a various iteration of coding a picture, mode select unit 40may effectively activate a parameter set for a particular sequence ofpictures, view, view component, depth component and/or texturecomponent. Moreover, mode select unit 40 may activate differentparameter sets in this manner for texture and depth components that eachbelong to the same view component in the manner described below in moredetail.

Additionally, mode select unit 40 may activate a parameter set for thedepth component of the view component based at least on the view orderindex value assigned to the view component of the 3DVC data. That is, insome instances, mode select unit 40 may activate a texture-specificparameter set for the texture component of a view component and thenactivate yet another parameter set specifically for the depth componentof the same view component. As a result, mode select unit 40 may encodethe depth component of the view component based on the parameter setactivated for the depth component of the view component and not theactivated texture parameter set. Mode select unit 40 may encode thetexture component based on the activated texture parameter set. In thisway, the techniques may promote separate activation of parameter sets,such as a PPS or SPS, for texture and depth components of a viewcomponent, providing a way by which to facilitate separate handling orprocessing of depth and texture components in 3DVC.

Video encoder 20 may also separately remove texture and depth componentsfrom a decoded picture buffer, which is shown as reference picturememory 64 in the example of FIG. 2. Because the techniques set forth inthis disclosure enable separate handling of texture and depthcomponents, video encoder 20 may code a texture component of a viewcomponent using reference pictures different than those used when codinga depth component of the same view component contrary to conventional3DVC where a view component (and therefore the depth and texturecomponents of that view component) was coded using the same referencepictures. As a result, there may be instances where depth components ofa reference view component may be removed from the decoded picturebuffer prior to texture components of the same reference view component,and a texture component of a reference view component may be removedfrom the decoded picture buffer prior to the depth component of the samereference view component.

In operation, mode select unit 40 of video encoder 20 may be configuredto perform the techniques described in this disclosure. Mode select unit40 may store a depth component in reference picture memory 64 andanalyze a view dependency to determine whether the depth component isused for inter-view prediction. Mode select unit 40 may then remove thedepth component from reference picture memory 64 in response todetermining that the depth component is not used for inter-viewprediction. That is, mode select unit 40 may remove the depth componentof a reference view component from reference picture memory 64 withoutremoving the texture component of the same reference view component inresponse to determining that the depth component is not used forinter-view prediction. Mode select unit 40 may, prior to removing thedepth component, validate this depth component as being eligible forremoval by determining that the depth component does not belong to atarget output view and that the depth component is associated with anetwork abstraction layer reference identification code having a valueequal to zero (meaning that the content of the NAL unit encapsulatingthe depth component is not used to construct reference pictures forinter-picture prediction).

FIG. 3 is a block diagram illustrating an example video decoder 30 thatmay implement the techniques described in this disclosure for decoding amultiview bitstream. In the example of FIG. 3, video decoder 30 includesan entropy decoding unit 80, prediction unit 81 having motioncompensation unit 82 and intra prediction unit 84, inverse quantizationunit 86, inverse transformation unit 88, summer 90, and referencepicture memory 92.

During the decoding process, video decoder 30 receives an encoded videobitstream that represents video blocks of an encoded video slice andassociated syntax elements from video encoder 20. Entropy decoding unit80 of video decoder 30 entropy decodes the bitstream to generatequantized coefficients, motion vectors, and other syntax elements.Entropy decoding unit 80 forwards the motion vectors and other syntaxelements to prediction unit 81. Video decoder 30 may receive the syntaxelements at the video slice level and/or the video block level.

For example, video decoder 30 may receive a number of NAL units having aNAL unit header that identifies a type of data stored to the NAL unit(e.g., VCL data and non-VCL data). Parameter sets may contain thesequence-level header information, such as an SPS, PPS, or otherparameter set described above.

According to aspects of this disclosure, video decoder 30 may activate aparameter set as a texture parameter set for the texture component ofthe view component based at least on a view order index value assignedto the view component of the 3DVC data. More specifically, entropydecoding unit 80 may parse the parameter sets from the bitstream,decoding the parameter sets and providing the decoded parameter sets tothe other components of video decoder 30, such as prediction unit 81,inverse quantization unit 86 and inverse transform processing unit 88.Each of these components may refer to the currently active parametersets and in this sense, video decoder 30 activates the parameter set foreach component of video decoder 30.

In any event, the view order index may, as noted above, describe thedecoding order of a corresponding view component of an access unit. Theview order index can be used with a picture order count (POC) value or aframe value to identify a view component of a bitstream. This aspect ofthe techniques may therefore provide for a parameter set, such as a PPSor SPS, that is activated only for the texture component of a viewcomponent and does not apply to the corresponding depth component of thesame view component. In this respect, video decoder 30 may decode onlythe texture component of the view component and not the depth componentof the view component based on the activated texture parameter set.

Additionally, video decoder 30 may activate a parameter set for thedepth component of the view component based at least on the view orderindex value assigned to the view component of the 3DV data. That is, insome instances, the video coding device may activate a texture-specificparameter set for the texture component of a view component and thenactivate yet another parameter set specifically for the depth componentof the same view component. As a result, video decoder 30 may code thedepth component of the view component based on the parameter setactivated for the depth component of the view component and not theactivated texture parameter set. Video decoder 30 may decode the texturecomponent based on the activated texture parameter set. In this way, thetechniques may promote separate activation of parameter sets, such as aPPS or SPS, for texture and depth components of a view component,providing a way by which to facilitate separate handling or processingof depth and texture components in 3DVC.

In detail, this aspect of the techniques may enable a video coder (whichmay generally refer to both or either of a video encoder and/or a videodecoder) to activate a separate parameter set for each of a depthcomponent and a texture component. The sequence and picture parameterset mechanism may effectively decouple the transmission of infrequentlychanging information from the transmission of coded macroblock data.Sequence and picture parameter sets may, in some applications, beconveyed out-of-band using a reliable transport mechanism. A pictureparameter set raw byte sequence payload (or “RBSP,” which is anothermore formal way to refer to a picture parameter set) includes parametersthat can be referred to by the coded slice NAL units of one or moretexture or depth components of one or more view components. A sequenceparameter set RBSP includes parameters that can be referred to by one ormore picture parameter set or one or more buffering period SEI messages.

When decoding a 3DVC bitstream containing depth views, at any givenmoment during the operation of the decoding process, video decoder 30may activate zero or one active picture parameter sets, zero or moreactive texture picture parameter sets, and zero or more active viewpicture parameter sets. Each active texture picture parameter set isactive specifically for a particular view order index value less than orequal to the maximum view order index value, and each active viewpicture parameter set is active specifically for a particular view orderindex value that is less than the maximum view order index value.

Similarly, at a given moment during the operation of the decodingprocess, video decoder 30 may activate zero or one active MVC sequenceparameter sets, zero or more active texture MVC sequence parameter sets,and zero or more active view MVC sequence parameter sets. Each activetexture MVC sequence parameter set is active specifically for aparticular view order index value less than or equal to the maximum vieworder index value, and each active view MVC sequence parameter set isactive specifically for a particular view order index value that is lessthan the maximum view order index value.

In this sense, activation of parameter set for 3DVC generally is similarto activation of parameter sets in MVC, except for those differencesnoted herein (that involve instances of how to handle depth viewcomponents that are currently not supported in MVC). Moreover, MVCprovides for a number of reserved bits in each parameter set to whichadditional syntax elements directed to extensions using MVC, such as3DVC, may utilize to specify 3DVC-specific syntax elements. By providingthese reserved bits, the parameter sets maintain backwards compatibilitywith MVC even though these reserve bits may be utilized to specifysyntax elements unrelated to or not specified in the MVC extension toH.264/AVC. For this reason, even though the MVC parameter set mayinclude additional syntax elements unrelated to MVC, these parametersets are referred to as MVC parameter sets given the reserved bitspresent in the MVC parameter sets.

The detailed activation process for picture and sequence parameter setsis as follows. Video decoder 30 initially considers each pictureparameter set RBSP as not active at the start of the operation of thedecoding process. At most, video decoder 30 activates one pictureparameter set RBSP as the active picture parameter set RBSP at any givenmoment during the operation of the decoding process. When any particularpicture parameter set RBSP becomes the active picture parameter setRBSP, video decoder 30 effectively de-activates the previously-activepicture parameter set RBSP (if any).

In addition to the active picture parameter set RBSP, video decoder 30may activate zero or more picture parameter set RBSPs specifically fortexture components (with a particular view order index value (“VOIdx”)less than or equal to the maximum view order index value (“VOIdxMax”))that belong to the target output views or that may be referred tothrough inter-view prediction in decoding texture components belongingto the target output views. Such a picture parameter set RBSP isreferred to as the active view picture parameter set RBSP for theparticular value of VOIdx. The restrictions on active picture parameterset RBSPs also apply to active view picture parameter set RBSPs for aparticular value of VOIdx.

Furthermore, video decoder 30 may activate zero or more pictureparameter set RBSPs specifically for view components (with a particularvalue of VOIdx less than VOIdxMax) that belong to the target outputviews or that may be referred to through inter-view prediction indecoding depth components belonging to the target output views. Such apicture parameter set RBSP is referred to as the active view pictureparameter set RBSP for the particular value of VOIdx. The restrictionson active picture parameter set RBSPs also apply to active view pictureparameter set RBSPs for a particular value of VOIdx less than VOIdxMax.

When a picture parameter set RBSP (with a particular value ofpic_parameter_set_id) is not the active picture parameter set RBSP andthe picture parameter set RBSP is referred to by a coded slice NAL unitbelonging to a depth component and with VOIdx equal to VOIdxMax (usingthat value of pic_parameter_set_id), video decoder 30 may activate thepicture parameter set RBSP. A coded slice NAL unit belonging to a depthcomponent may have a nal_unit_type equal to 21. This picture parameterset RBSP is called the active picture parameter set RBSP until thepicture parameter set RBSP is deactivated when another picture parameterset RBSP becomes the active picture parameter set RBSP. A pictureparameter set RBSP, with that particular value of pic_parameter_set_id,shall be available to the decoding process prior to activation of thepicture parameter set RBSP.

When a picture parameter set RBSP (with a particular value ofpic_parameter_set_id) is not the active view picture parameter set for aparticular value of VOIdx less than VOIdxMax and the picture parameterset RBSP is referred to by a coded slice NAL unit belonging to a depthcomponent (i.e., with nal_unit_type equal to 21) and with the particularvalue of VOIdx (using that value of pic_parameter_set_id), video decoder30 activates the picture parameter set RBSP for view components with theparticular value of VOIdx. This picture parameter set RBSP is called theactive view picture parameter set RBSP for the particular value of VOIdxuntil the picture parameter set RBSP is deactivated when another pictureparameter set RBSP becomes the active view picture parameter set RBSPfor the particular value of VOIdx. A picture parameter set RBSP, withthat particular value of pic_parameter_set_id, shall be available to thedecoding process prior to activation of the picture parameter set RBSP.

When a picture parameter set RBSP (with a particular value ofpic_parameter_set_id) is not the active texture picture parameter setfor a particular value of VOIdx less than or equal to VOIdxMax and thepicture parameter set RBSP is referred to by a coded slice NAL unitbelonging to a texture component (i.e., with nal_unit_type equal to 1, 5or 20) and with the particular value of VOIdx (using that value ofpic_parameter_set_id), video decoder 30 activates the picture parameterset RBSP for depth components with the particular value of VOIdx. Thispicture parameter set RBSP is called the active texture pictureparameter set RBSP for the particular value of VOIdx until the pictureparameter set RBSP is deactivated when another picture parameter setRBSP becomes the active texture picture parameter set RBSP for theparticular value of VOIdx. A picture parameter set RBSP, with thatparticular value of pic_parameter_set_id, shall be available to thedecoding process prior to activation of the picture parameter set RBSP.

Any picture parameter set NAL unit containing the value ofpic_parameter_set_id for the active picture parameter set RBSP for acoded picture shall have the same content as that of the active pictureparameter set RBSP for this coded picture unless the picture parameterset NAL unit follows the last VCL NAL unit of this coded picture andprecedes the first VCL NAL unit of another coded picture. Any pictureparameter set NAL unit containing the value of pic_parameter_set_id forthe active view picture parameter set RBSP for a particular value ofVOIdx less than VOIdxMax for a coded picture shall have the same contentas that of the active view picture parameter set RBSP for the particularvalue of VOIdx for this coded picture unless the picture parameter setNAL unit follows the last VCL NAL unit of this coded picture andprecedes the first VCL NAL unit of another coded picture. Any pictureparameter set NAL unit containing the value of pic_parameter_set_id forthe active texture picture parameter set RBSP for a particular value ofVOIdx for a coded picture shall have the same content as that of theactive texture picture parameter set RBSP for the particular value ofVOIdx for this coded picture unless the picture parameter set NAL unitfollows the last VCL NAL unit of this coded picture and precedes thefirst VCL NAL unit of another coded picture.

Video decoder 30 initially determines that each MVC sequence parameterset RBSP is not active at the start of the operation of the decodingprocess. Again, reference to MVC sequence parameter sets refers to MVCsequence parameter sets within the context of 3DVC, which inherits orotherwise adopts MVC and thus incorporates MVC sequence parameter sets(although these parameter sets may be modified by adding additional 3DVCspecific syntax elements). At most, video decoder 30 determines that oneMVC sequence parameter set RBSP is the active MVC sequence parameter setRBSP at any given moment during the operation of the decoding process.When any particular MVC sequence parameter set RBSP becomes the activeMVC sequence parameter set RBSP, video decoder 30 deactivates thepreviously-active MVC sequence parameter set RBSP (if any).

The active MVC sequence parameter set RBSP is either a sequenceparameter set RBSP or a subset sequence parameter set RBSP. Sequenceparameter set RBSPs are activated by coded slice NAL units withnal_unit_type equal to 1 or 5 or buffering period SEI messages that arenot included in an MVC scalable nesting SEI message or a 3DV scalablenesting SEI message. Subset sequence parameter sets are activated bycoded slice MVC extension NAL units (nal_unit_type equal to 21) orbuffering period SEI messages that are included in a 3DV scalablenesting SEI message. A sequence parameter set RBSP and a subset sequenceparameter set RBSP may have the same value of seq_parameter_set_id.

In addition to the active MVC sequence parameter set RBSP, video decoder30 may activate zero or more MVC sequence parameter set RBSPsspecifically for view components (with a particular value of VOIdx lessthan VOIdxMax) that belong to the target output views or that may bereferred to through inter-view prediction in decoding view componentsbelonging to the target output views. Such an MVC sequence parameter setRBSP is referred to as the active view MVC sequence parameter set RBSPfor the particular value of VOIdx. The restrictions on active MVCsequence parameter set RBSPs also apply to active view MVC sequenceparameter set RBSPs for a particular value of VOIdx less than VOIdxMax.

Furthermore, video decoder 30 may activate zero or more MVC sequenceparameter set RBSPs specifically for texture components (with aparticular value of VOIdx less than or equal to VOIdxMax) that belong tothe target output views or that may be referred to through inter-viewprediction in decoding texture components belonging to the target outputviews. Such an MVC sequence parameter set RBSP is referred to as theactive texture MVC sequence parameter set RBSP for the particular valueof VOIdx. The restrictions on active MVC sequence parameter set RBSPsalso apply to active texture MVC sequence parameter set RBSPs for aparticular value of VOIdx.

For the following description, the activating buffering period SEImessage is specified as follows.

If VOIdxMax is equal to VOIdxMin and the access unit contains abuffering period SEI message not included in an MVC scalable nesting SEImessage and not included in a 3DVC scalable nesting SEI message, thisbuffering period SEI message is the activating buffering period SEImessage.

Otherwise, if VOIdxMax is not equal to VOIdxMin and the access unitcontains a buffering period SEI message included in a 3DVC scalablenesting SEI message and associated with the operation point beingdecoded, this buffering period SEI message is the activating bufferingperiod SEI message.

Otherwise, the access unit does not contain an activating bufferingperiod SEI message.

When a sequence parameter set RBSP (nal_unit_type is equal to 7) with aparticular value of seq_parameter_set_id is not already the active MVCsequence parameter set RBSP and the sequence parameter set RBSP isreferred to by activation of a picture parameter set RBSP (using thatvalue of seq_parameter_set_id) and the picture parameter set RBSP isactivated by a coded slice NAL unit with nal_unit_type equal to 1 or 5(the picture parameter set RBSP becomes the active picture parameter setRBSP and VOIdxMax is equal to VOIdxMin and there is no depth componentin the access unit) and the access unit does not contain an activatingbuffering period SEI message, video decoder 30 may activate the sequenceparameter set RBSP. This sequence parameter set RBSP is called theactive MVC sequence parameter set RBSP until the sequence parameter setRBSP is deactivated when another MVC sequence parameter set RBSP becomesthe active MVC sequence parameter set RBSP. A sequence parameter setRBSP, with that particular value of seq_parameter_set_id, shall beavailable to the decoding process prior to activation of the sequenceparameter set RBSP.

When a sequence parameter set RBSP (nal_unit_type is equal to 7) with aparticular value of seq_parameter_set_id is not already the active MVCsequence parameter set RBSP and the sequence parameter set RBSP isreferred to by an activating buffering period SEI message (using thatvalue of seq_parameter_set_id) that is not included in a 3DV scalablenesting SEI message and VOIdxMax is equal to VOIdxMin and there is nodepth component in the access unit, video decoder 30 activates thesequence parameter set RBSP. This sequence parameter set RBSP is calledthe active MVC sequence parameter set RBSP until the sequence parameterset RBSP is deactivated when another MVC sequence parameter set RBSPbecomes the active MVC sequence parameter set RBSP. A sequence parameterset RBSP, with that particular value of seq_parameter_set_id, shall beavailable to the decoding process prior to activation of the sequenceparameter set RBSP.

When a subset sequence parameter set RBSP (nal_unit_type is equal to 15)with a particular value of seq_parameter_set_id is not already theactive MVC sequence parameter set RBSP and the subset sequence parameterset RBSP is referred to by activation of a picture parameter set RBSP(using that value of seq_parameter_set_id) and the picture parameter setRBSP is activated by a coded slice NAL unit with nal_unit_type equal to21 and with VOIdx equal to VOIdxMax (the picture parameter set RBSPbecomes the active picture parameter set RBSP) and the access unit doesnot contain an activating buffering period SEI message, video decoder 30may activate the subset sequence parameter set RBSP. This subsetsequence parameter set RBSP is called the active MVC sequence parameterset RBSP until the subset sequence parameter set RBSP is deactivatedwhen another MVC sequence parameter set RBSP becomes the active MVCsequence parameter set RBSP. A subset sequence parameter set RBSP, withthat particular value of seq_parameter_set_id, shall be available to thedecoding process prior to its activation.

When a subset sequence parameter set RBSP (nal_unit_type is equal to 15)with a particular value of seq_parameter_set_id is not already theactive MVC sequence parameter set RBSP and the subset sequence parameterset RBSP is referred to by an activating buffering period SEI message(using that value of seq_parameter_set_id) that is included in a 3DVscalable nesting SEI message, video decoder 30 activates the subsetsequence parameter set RBSP. This subset sequence parameter set RBSP iscalled the active MVC sequence parameter set RBSP until the subsetsequence parameter set RBSP is deactivated when another MVC sequenceparameter set RBSP becomes the active MVC sequence parameter set RBSP. Asubset sequence parameter set RBSP, with that particular value ofseq_parameter_set_id, shall be available to the decoding process priorto activation of the subset sequence parameter set RBSP.

For the following description, the activating texture buffering periodSEI message for a particular value of VOIdx is specified as follows.

If the access unit contains one or more than one buffering period SEImessage included in an MVC scalable nesting SEI message and associatedwith an operation point for which the greatest VOIdx in the associatedbitstream subset is equal to the particular value of VOIdx, the first ofthese buffering period SEI messages, in decoding order, is theactivating texture buffering period SEI message for the particular valueof VOIdx.

Otherwise, if the access unit contains a buffering period SEI messagenot included in an MVC scalable nesting SEI message or a 3DV scalablenesting SEI message, this buffering period SEI message is the activatingtexture buffering period SEI message for the particular value of VOIdxequal to VOIdxMin.

Otherwise, the access unit does not contain an activating texturebuffering period SEI message for the particular value of VOIdx.

When a sequence parameter set RBSP (nal_unit_type is equal to 7) with aparticular value of seq_parameter_set_id is not already the activetexture MVC sequence parameter set RBSP for VOIdx equal to VOIdxMin andthe sequence parameter set RBSP is referred to by activation of apicture parameter set RBSP (using that value of seq_parameter_set_id)and the picture parameter set RBSP is activated by a coded slice NALunit with nal_unit_type equal to 1 or 5 (the picture parameter set RBSPbecomes the active texture picture parameter set RBSP for VOIdx equal toVOIdxMin), video decoder 30 may activate the sequence parameter set RBSPfor texture components with VOIdx equal to VOIdxMin. This sequenceparameter set RBSP is called the active texture MVC sequence parameterset RBSP for VOIdx equal to VOIdxMin until the sequence parameter setRBSP is deactivated when another MVC sequence parameter set RBSP becomesthe active texture MVC sequence parameter set RBSP for VOIdx equal toVOIdxMin. A sequence parameter set RBSP, with that particular value ofseq_parameter_set_id, shall be available to the decoding process priorto activation of the sequence parameter set RBSP.

When a sequence parameter set RBSP (nal_unit_type is equal to 7) with aparticular value of seq_parameter_set_id is not already the activetexture MVC sequence parameter set RBSP for VOIdx equal to VOIdxMin andthe sequence parameter set RBSP is referred to by an activating texturebuffering period SEI message (using that value of seq_parameter_set_id)that is not included in an MVC scalable nesting SEI message or a 3DVscalable nesting SEI message, video decoder 30 may activate the sequenceparameter set RBSP for texture components with VOIdx equal to VOIdxMin.This sequence parameter set RBSP is called the active texture MVCsequence parameter set RBSP for VOIdx equal to VOIdxMin until thesequence parameter set RBSP is deactivated when another MVC sequenceparameter set RBSP becomes the active texture MVC sequence parameter setRBSP for VOIdx equal to. A sequence parameter set RBSP, with thatparticular value of seq_parameter_set_id, shall be available to thedecoding process prior to activation of the sequence parameter set RBSP.

When a subset sequence parameter set RBSP (nal_unit_type is equal to 15)with a particular value of seq_parameter_set_id is not already theactive texture MVC sequence parameter set RBSP for a particular value ofVOIdx less than or equal to VOIdxMax and the subset sequence parameterset RBSP is referred to by activation of a picture parameter set RBSP(using that value of seq_parameter_set_id) and the picture parameter setRBSP is activated by a coded slice MVC extension NAL unit (nal_unit_typeequal to 20) with the particular value of VOIdx (the picture parameterset RBSP becomes the active texture picture parameter set RBSP for theparticular value of VOIdx), video decoder 30 may activate the subsetsequence parameter set RBSP for texture components with the particularvalue of VOIdx. This subset sequence parameter set RBSP is called theactive texture MVC sequence parameter set RBSP for the particular valueof VOIdx until the subset sequence parameter set RBSP is deactivatedwhen another MVC sequence parameter set RBSP becomes the active textureMVC sequence parameter set RBSP for the particular value of VOIdx. Asubset sequence parameter set RBSP, with that particular value ofseq_parameter_set_id, shall be available to the decoding process priorto activation of the subset sequence parameter set RBSP.

When a subset sequence parameter set RBSP (nal_unit_type is equal to 15)with a particular value of seq_parameter_set_id is not already theactive texture MVC sequence parameter set RBSP for a particular value ofVOIdx less than or equal to VOIdxMax and the subset sequence parameterset RBSP is referred to by an activating texture buffering period SEImessage (using that value of seq_parameter_set_id) that is included inan MVC scalable nesting SEI message and associated with the particularvalue of VOIdx, video decoder 30 may activate this subset sequenceparameter set RBSP for texture components with the particular value ofVOIdx. This subset sequence parameter set RBSP is called the activetexture MVC sequence parameter set RBSP for the particular value ofVOIdx until the subset sequence parameter set RBSP is deactivated whenanother MVC sequence parameter set RBSP becomes the active texture MVCsequence parameter set RBSP for the particular value of VOIdx. A subsetsequence parameter set RBSP, with that particular value ofseq_parameter_set_id, shall be available to the decoding process priorto activation of the subset sequence parameter set RBSP.

For the following specification, the activating view buffering periodSEI message for a particular value of VOIdx is specified as follows.

If the access unit contains one or more than one buffering period SEImessage included in a 3DVC scalable nesting SEI message and associatedwith an operation point for which the greatest VOIdx in the associatedbitstream subset is equal to the particular value of VOIdx, the first ofthese buffering period SEI messages, in decoding order, is theactivating view buffering period SEI message for the particular value ofVOIdx.

Otherwise, the access unit does not contain an activating view bufferingperiod SEI message for the particular value of VOIdx.

When a subset sequence parameter set RBSP (nal_unit_type is equal to 15)with a particular value of seq_parameter_set_id is not already theactive view MVC sequence parameter set RBSP for a particular value ofVOIdx less than VOIdxMax and the subset sequence parameter set RBSP isreferred to by activation of a picture parameter set RBSP (using thatvalue of seq_parameter_set_id) and the picture parameter set RBSP isactivated by a coded slice NAL unit with nal_unit_type equal to 21 andwith the particular value of VOIdx (the picture parameter set RBSPbecomes the active view picture parameter set RBSP for the particularvalue of VOIdx), video decoder 30 activates the subset sequenceparameter set RBSP for view components with the particular value ofVOIdx. This subset sequence parameter set RBSP is called the active viewMVC sequence parameter set RBSP for the particular value of VOIdx untilthe subset sequence parameter set RBSP is deactivated when another MVCsequence parameter set RBSP becomes the active view MVC sequenceparameter set RBSP for the particular value of VOIdx or when decoding anaccess unit with VOIdxMax less than or equal to the particular value ofVOIdx. A subset sequence parameter set RBSP, with that particular valueof seq_parameter_set_id, shall be available to the decoding processprior to activation of the subset sequence parameter set RBSP.

When a subset sequence parameter set RBSP (nal_unit_type is equal to 15)with a particular value of seq_parameter_set_id is not already theactive view MVC sequence parameter set RBSP for a particular value ofVOIdx less than VOIdxMax and the subset sequence parameter set RBSP isreferred to by an activating view buffering period SEI message (usingthat value of seq_parameter_set_id) that is included in a 3DV scalablenesting SEI message and associated with the particular value of VOIdx,video decoder 30 activates this subset sequence parameter set RBSP forview components with the particular value of VOIdx. This subset sequenceparameter set RBSP is called the active view MVC sequence parameter setRBSP for the particular value of VOIdx until the subset sequenceparameter set RBSP is deactivated when another MVC sequence parameterset RBSP becomes the active view MVC sequence parameter set RBSP for theparticular value of VOIdx or when decoding an access unit with VOIdxMaxless than or equal to the particular value of VOIdx. A subset sequenceparameter set RBSP, with that particular value of seq_parameter_set_id,shall be available to the decoding process prior to activation of thesubset sequence parameter set RBSP.

An MVC sequence parameter set RBSP that includes a value of profile_idcnot specified in Annex A or Annex H or proposed Annex I to H.264/AVCshall not be referred to by activation of a picture parameter set RBSPas the active picture parameter set RBSP or as active view pictureparameter set RBSP or as active texture picture parameter set RBSP(using that value of seq_parameter_set_id) or referred to by a bufferingperiod SEI message (using that value of seq_parameter_set_id). An MVCsequence parameter set RBSP including a value of profile_idc notspecified in Annex A or Annex H or proposed Annex I to H.264/AVC isignored in the decoding for profiles specified in Annex A or Annex H orproposed Annex I to H.264/AVC.

It is a requirement of bitstream conformance that the followingconstraints are obeyed:

For each particular value of VOIdx, all coded slice NAL units (withnal_unit_type equal to 1, 5, 20, or 21) of a coded video sequence shallrefer to the same value of seq_parameter_set_id (via the pictureparameter set RBSP that is referred to by the value ofpic_parameter_set_id).

The value of seq_parameter_set_id in a buffering period SEI message thatis not included in an MVC scalable nesting SEI message shall beidentical to the value of seq_parameter_set_id in the picture parameterset RBSP that is referred to by coded slice NAL units with nal_unit_typeequal to 1 or 5 (via the value of pic_parameter_set_id) in the sameaccess unit.

The value of seq_parameter_set_id in a buffering period SEI message thatis included in an MVC scalable nesting SEI message and is associatedwith a particular value of VOIdx shall be identical to the value ofseq_parameter_set_id in the picture parameter set RBSP that is referredto by coded slice NAL units with nal_unit_type equal to 1, 5 or 20 withthe particular value of VOIdx (via the value of pic_parameter_set_id) inthe same access unit.

The value of seq_parameter_set_id in a buffering period SEI message thatis included in a 3DVC scalable nesting SEI message and is associatedwith a particular value of VOIdx shall be identical to the value ofseq_parameter_set_id in the picture parameter set RBSP that is referredto by coded slice NAL units with nal_unit_type equal to 21 with theparticular value of VOIdx (via the value of pic_parameter_set_id) in thesame access unit.

The active view MVC sequence parameter set RBSPs for different values ofVOIdx may be the same MVC sequence parameter set RBSP. The active MVCsequence parameter set RBSP and an active view MVC sequence parameterset RBSP for a particular value of VOIdx may be the same MVC sequenceparameter set RBSP.

The active texture MVC sequence parameter set RBSPs for different valuesof VOIdx may be the same MVC sequence parameter set RBSP. The active MVCsequence parameter set RBSP and an active texture MVC sequence parameterset RBSP for a particular value of VOIdx may be the same MVC sequenceparameter set RBSP. An active view MVC sequence parameter set RBSP for aparticular value of VOIdx and an active texture MVC sequence parameterset RBSP for a particular value of VOIdx may be the same MVC sequenceparameter set RBSP.

When the active MVC sequence parameter set RBSP for a coded picture is asequence parameter set RBSP, any sequence parameter set RBSP in thecoded video sequence containing this coded picture and with the value ofseq_parameter_set_id for the active MVC sequence parameter set RBSPshall have the same content as that of the active MVC sequence parameterset RBSP.

When the active MVC sequence parameter set RBSP for a coded picture is asubset sequence parameter set RBSP, any subset sequence parameter setRBSP in the coded video sequence containing this coded picture and withthe value of seq_parameter_set_id for the active MVC sequence parameterset RBSP shall have the same content as that of the active MVC sequenceparameter set RBSP.

For each particular value of VOIdx, the following applies:

When the active texture MVC sequence parameter set RBSP for a codedpicture is a sequence parameter set RBSP, any sequence parameter setRBSP in the coded video sequence containing this coded picture and withthe value of seq_parameter_set_id for the active texture MVC sequenceparameter set RBSP shall have the same content as that of the activetexture MVC sequence parameter set RBSP.

When the active texture MVC sequence parameter set RBSP for a codedpicture is a subset sequence parameter set RBSP, any subset sequenceparameter set RBSP in the coded video sequence containing this codedpicture and with the value of seq_parameter_set_id for the activetexture MVC sequence parameter set RBSP shall have the same content asthat of the active texture MVC sequence parameter set RBSP.

The active view MVC sequence parameter set RBSP for a coded picture is asubset sequence parameter set RBSP, and any subset sequence parameterset RBSP in the coded video sequence containing this coded picture andwith the value of seq_parameter_set_id for the active view MVC sequenceparameter set RBSP shall have the same content as that of the activeview MVC sequence parameter set RBSP.

If picture parameter set RBSPs or MVC sequence parameter set RBSPs areconveyed within the bitstream, these constraints impose an orderconstraint on the NAL units that contain the picture parameter set RBSPsor MVC sequence parameter set RBSPs, respectively. Otherwise (pictureparameter set RBSPs or MVC sequence parameter set RBSPs are conveyed byother means not specified in this Recommendation|International Standardto the H.264 video coding standard), they must be available to thedecoding process in a timely fashion such that these constraints areobeyed.

When present, a sequence parameter set extension RBSP includesparameters having a similar function to those of a sequence parameterset RBSP. For purposes of establishing constraints on the syntaxelements of the sequence parameter set extension RBSP and for purposesof determining activation of a sequence parameter set extension RBSP,the sequence parameter set extension RBSP shall be considered part ofthe preceding sequence parameter set RBSP with the same value ofseq_parameter_set_id. When a sequence parameter set RBSP is present thatis not followed by a sequence parameter set extension RBSP with the samevalue of seq_parameter_set_id prior to the activation of the sequenceparameter set RBSP, the sequence parameter set extension RBSP and itssyntax elements shall be considered not present for the active MVCsequence parameter set RBSP. The contents of sequence parameter setextension RBSPs only apply when the base texture view, which conforms toone or more of the profiles specified in Annex A, of a coded videosequence conforming to one or more profiles specified in Annex I isdecoded. Subset sequence parameter set RBSPs shall not be followed by asequence parameter set extension RBSP.

Sequence parameter sets extension RBSPs are not considered to be part ofa subset sequence parameter set RBSP and subset sequence parameter setRBSPs must not be followed by a sequence parameter set extension RBSP.

For view components with VOIdx equal to VOIdxMax, all constraints thatare expressed on the relationship between the values of the syntaxelements (and the values of variables derived from those syntaxelements) in MVC sequence parameter sets and picture parameter sets andother syntax elements are expressions of constraints that apply only tothe active MVC sequence parameter set and the active picture parameterset. For view components with a particular value of VOIdx less thanVOIdxMax, all constraints that are expressed on the relationship betweenthe values of the syntax elements (and the values of variables derivedfrom those syntax elements) in MVC sequence parameter sets and pictureparameter sets and other syntax elements are expressions of constraintsthat apply only to the active view MVC sequence parameter set and theactive view picture parameter set for the particular value of VOIdx.

If any MVC sequence parameter set RBSP having profile_idc equal to thevalue of one of the profile_idc values specified in Annex A, Annex H orproposed Annex I is present that is never activated in the bitstream(i.e., the MVC sequence parameter set RBSP never becomes the active MVCsequence parameter set or an active view MVC sequence parameter set),syntax elements of the MVC sequence parameter set RBSP shall have valuesthat would conform to the specified constraints if the MVC sequenceparameter set RBSP were activated by reference in anotherwise-conforming bitstream. If any picture parameter set RBSP ispresent that is never activated in the bitstream (i.e., the pictureparameter set RBSP never becomes the active picture parameter set or anactive view picture parameter set), syntax elements of the pictureparameter set RBSP shall have values that would conform to the specifiedconstraints if the picture parameter set RBSP were activated byreference in an otherwise-conforming bitstream.

During operation of the decoding process, for view components with VOIdxequal to VOIdxMax, the values of parameters of the active pictureparameter set and the active MVC sequence parameter set shall beconsidered in effect (meaning, in one example, applied when decoding).For view components with a particular value of VOIdx less than VOIdxMax,the values of the parameters of the active view picture parameter setand the active view MVC sequence parameter set for the particular valueof VOIdx shall be considered in effect. For interpretation of SEImessages that apply to the entire access unit or the view component withVOIdx equal to VOIdxMax, the values of the parameters of the activepicture parameter set and the active MVC sequence parameter set for thesame access unit shall be considered in effect unless otherwisespecified in the SEI message semantics. For interpretation of SEImessages that apply to view components with a particular value of VOIdxless than VOIdxMax, the values of the parameters of the active viewpicture parameter set and the active view MVC sequence parameter set forthe particular value of VOIdx for the same access unit shall beconsidered in effect unless otherwise specified in the SEI messagesemantics.

For any active MVC SPS or active view MVC SPS, part of the syntaxelements in the MVC SPS extension applies only to the depth viewsreferring to this SPS, while the some other parts of the syntax elementsin the MVC SPS extension collectively apply to both the depth viewsreferring to this SPS and the corresponding texture views. Morespecifically, the view dependency information of the MVC SPS extensionapplies only to the depth views, and the level definitions collectivelyapply to operation points, each of which contains both depth views andtheir corresponding texture views.

In some instances, the techniques of this disclosure may enable videodecoder 30 to activate, during coding of a bitstream that contains depthviews, a texture picture parameter set (PPS) or a texture MVC sequenceparameter set (SPS) for a view order index value.

In some instances, video decoder 30 may activate, during coding of thebitstream, an active PPS, activate, during coding of the bitstream, anactive view PPS for the view order index value, activate, during codingof the bitstream, an active view MVC SPS for the view order index value,and activate, during coding of the bitstream, an active MVC SPS.

In some instances, activating the texture PPS may involve activating,for depth components that specify the view order index value, a PPS rawbyte sequence payload (RBSP) when the PPS RBSP is not an active texturePPS for the view order index value and the PPS RBSP is referred to by acoded slice Network Abstraction Layer (NAL) unit that both belongs to atexture component and that specifies the view order index value,activating the PPS RBSP. Video decoder 30 may also activate the texturePPS and the texture MVC SPS as described above.

In any event, when the video slice is coded as an intra-coded (I) slice,intra prediction unit 84 of prediction unit 81 may generate predictiondata for a video block of the current video slice based on a signaledintra prediction mode and data from previously decoded blocks of thecurrent picture in view of the active parameter sets. When the pictureis coded as an inter-coded (i.e., B, P or generalize PB (GPB)) slice,motion compensation unit 82 of prediction unit 81 produces predictiveblocks for a video block of the current video slice based on the motionvectors and other syntax elements received from entropy decoding unit80, again in view of the active parameter sets. The predictive blocksmay be produced from one of the reference pictures within one of thereference picture lists. Video decoder 30 may construct the referencepicture lists, List 0 and List 1 (or a combined list, List c) usingdefault construction techniques based on reference pictures stored inreference picture memory 92.

Motion compensation unit 82 determines prediction information for avideo block of the current video slice by parsing the motion vectors andother syntax elements, and uses the prediction information to producethe predictive blocks for the current video block being decoded. Forexample, motion compensation unit 82 uses some of the received syntaxelements to determine a prediction mode (e.g., intra- orinter-prediction) used to code the video blocks of the video slice, aninter-prediction slice type (e.g., B slice, P slice, or GPB slice),construction information for one or more of the reference picture listsfor the slice, motion vectors for each inter-encoded video block of theslice, inter-prediction status for each inter-coded video block of theslice, and other information to decode the video blocks in the currentvideo slice.

Inverse quantization unit 86 inverse quantizes, i.e., de-quantizes, thequantized transform coefficients provided in the bitstream and decodedby entropy decoding unit 80. The inverse quantization process mayinclude use of a quantization parameter calculated by video encoder 20for each video block in the video slice to determine a degree ofquantization and, likewise, a degree of inverse quantization that shouldbe applied.

Inverse transform processing unit 88 applies an inverse transform, e.g.,an inverse DCT, an inverse integer transform, or a conceptually similarinverse transform process, to the transform coefficients in order toproduce residual blocks in the pixel domain. Inverse transformprocessing unit 88 may determine the manner in which transforms wereapplied to residual data.

After motion compensation unit 82 generates the predictive block for thecurrent video block based on the motion vectors and other syntaxelements, video decoder 30 forms a decoded video block by summing theresidual blocks from inverse transform processing unit 88 with thecorresponding predictive blocks generated by motion compensation unit82. Summer 90 represents the component or components that perform thissummation operation. If desired, a deblocking filter may also be appliedto filter the decoded blocks in order to remove blockiness artifacts.Other loop filters (either in the coding loop or after the coding loop)may also be used to smooth pixel transitions, or otherwise improve thevideo quality. The decoded video blocks in a given picture are thenstored in reference picture memory 92, which stores reference picturesused for subsequent motion compensation. Reference picture memory 92also stores decoded video for later presentation on a display device,such as display device 32 of FIG. 1.

Other aspects of the techniques described in this disclosure may promoteseparate handling of depth and texture components by enabling a videocoding device to separately remove texture and depth components from adecoded picture buffer. The decoded picture buffer refers to a memory orother computer-readable medium capable of storing reference pictures foruse in coding a current view component. The decoded picture buffer isshown as reference picture memory 92 in the example of FIG. 3. Becausethe techniques set forth in this disclosure enable separate handling oftexture and depth components, video decoder 30 may decode a texturecomponent of a view component using reference pictures different thanthose used when coding a depth component of the same view componentcontrary to conventional 3DVC where a view component (and therefore thedepth and texture components of that view component) was coded using thesame reference pictures given treatment of views in MVC. As a result,there may be instances where depth components of a reference viewcomponent may be removed from the decoded picture buffer prior totexture components of the same reference view component, and a texturecomponent of a reference view component may be removed from the decodedpicture buffer prior to the depth component of the same reference viewcomponent.

In operation, video decoder 30 may perform the techniques described inthis disclosure by storing a depth component in reference picture memory92 and analyzing a view dependency to determine whether the depthcomponent is used for inter-view prediction. Video decoder 30 may thenremove the depth component from reference picture memory 92 in responseto determining that the depth component is not used for inter-viewprediction. That is, video decoder 30 may remove the depth component ofa reference view component from reference picture memory 92 withoutremoving the texture component of the same reference view component inresponse to determining that the depth component is not used forinter-view prediction. Video decoder 30 may, prior to removing the depthcomponent, validate this depth component as being eligible for removalby determining that the depth component does not belong to a targetoutput view and that the depth component is associated with a networkabstraction layer reference identification code having a value equal tozero (meaning that the content of the NAL unit encapsulating the depthcomponent is not used to construct reference pictures for inter-pictureprediction).

That is, in 3DVC (which again may also be referred to as MVC plus depthor MVC+D), the texture or depth portion of each view has its ownreference picture marking processes. The texture and depth componentsbelonging to the target output views may be outputted simultaneously.

For a depth component which does not belong to a target output view andhas nal_ref_idc equal to 0, video decoder 30 may remove the depthcomponent from the DPB once the depth component is never used forinter-view reference, by analyzing the view dependency signaled in theMVC SPS extension of the subset SPS containing a 3DV profile and iscurrently activated as the active view MVC sequence parameter set RBSP.Again, reference to MVC in this disclosure refers to MVC in the contextof 3DVC, which as noted above is a proposed extension of H.264.

For instance, the techniques of this disclosure may enable a video coder(which may refer to both or either of video encoder 20 and/or videodecoder 30) to store a depth component in a decoded picture buffer, thedepth component not belonging to a target output view and having anal_ref_idc equal to 0. Furthermore, a video coder may analyze a viewdependency to determine whether the depth component is never used tointer-view reference. In addition, the video coder may comprise removinga depth component from a decoded picture buffer in response todetermining that the depth component is never used for inter-viewreference. The view dependency may be signaled in a MVC sequenceparameter set (SPS) extension of a subset SPS, the subset SPS containinga 3DV profile, the subset SPS being currently activated as an activeview MVC sequence parameter set. The video encoder may encode the depthcomponent. Alternatively, the video coder may decode the depthcomponent.

While various aspects of the techniques are described above with respectto one of video encoder 20 or video decoder 30, the techniques may insome instances be implemented by both video encoder 20 and video decoder30 in a same or reciprocal fashion. As a result, the techniques may begenerally implemented by a video coder, which may represent a term usedin this disclosure to refer to both or only one of video encoder 20 andvideo decoder 30. These techniques should therefore not be limited inthis respect, but may generally be implemented by any video coder.

FIG. 4 is a block diagram illustrating encapsulation unit 21 in moredetail. In the example of FIG. 4, encapsulation unit 21 includes a videoinput interface 100, an audio input interface 102, a video file creationunit 104, and a video file output interface 106. Video file creationunit 104, in this example, includes a supplemental enhancementinformation (SEI) message generation unit 108, a view identifier (ID)assignment unit 110, a representation creation unit 112, and anoperation point creation unit 114.

Video input interface 100 and audio input interface 102 receive encodedvideo and audio data, respectively. While not shown in the example ofFIG. 1, source device 12 may also include an audio source and audioencoder to generate audio data and encode audio data, respectively.Encapsulation unit 21 may then encapsulate the encoded audio data andthe encoded video data to form a video file. Video input interface 100and audio input interface 102 may receive encoded video and audio dataas the data is encoded, or may retrieve encoded video and audio datafrom a computer-readable medium. Upon receiving encoded video and audiodata, video input interface 100 and audio input interface 102 pass theencoded video and audio data to video file creation unit 104 forassembly into a video file.

Video file creation unit 104 may correspond to a control unit includinghardware, software, and/or firmware configured to perform the functionsand procedures attributed thereto. The control unit may further performthe functions attributed to encapsulation unit 21 generally. Forexamples in which video file creation unit 104 is embodied in softwareand/or firmware, encapsulation unit 21 may include a computer-readablemedium comprising instructions for video file creation unit 104 and aprocessing unit to execute the instructions. Each of the sub-units ofvideo file creation unit 104 (SEI message generation unit 108, view IDassignment unit 110, representation creation unit 112, and operationpoint creation unit 114, in this example) may be implemented asindividual hardware units and/or software modules, and may befunctionally integrated or further separated into additional sub-units.

Video file creation unit 104 may correspond to any suitable processingunit or processing circuitry, such as, for example, one or moremicroprocessors, application-specific integrated circuits (ASICs), fieldprogrammable gate arrays (FPGAs), digital signal processors (DSPs), orany combination thereof. Video file creation unit 104 may furtherinclude a non-transitory computer-readable medium storing instructionsfor any or all of SEI message generation unit 108, view ID assignmentunit 110, representation creation unit 112, and operation point creationunit 114, as well as a processor for executing the instructions.

In general, video file creation unit 104 may create one or more videofiles including the received audio and video data. Video file creationunit 104 may construct a media presentation description (MPD) formultimedia content including two or more views. In other examples, videofile creation unit 104 may create a manifest storing data similar tothat of the MPD for the multimedia content. SEI message generation unit108 may represent a unit that generates SEI messages. View ID assignmentunit 110 may assign view identifiers to each of the views of themultimedia content. Representation creation unit 112 may construct oneor more representations for the multimedia content, each of which mayinclude one or more of the views for the multimedia content. In someexamples, view ID assignment unit 110 may include data in the MPD and/orthe representations (e.g., header data for the representations)indicating a maximum and a minimum of the view identifiers for viewsincluded in the representations. In addition, representation creationunit 112 may provide information in the MPD that indicates whetherlarger view IDs correspond to views having camera perspectives to theright or to the left of camera perspectives for views having smallerview IDs.

In some examples, the same view may be encoded using various encodingcharacteristics, such as different frame rates, different bit rates,different encoding schemes, or other differences. Representationcreation unit 112 may ensure that each view included in a commonrepresentation is encoded according to the same encodingcharacteristics. In this manner, the MPD and/or header data for therepresentation may signal a set of characteristics (or attributes) forthe representation that applies to all views in the representation.Moreover, representation creation unit 112 may create multiplerepresentations including the same views, albeit with potentiallydifferent encoding characteristics. In some examples, representationcreation unit 112 may encapsulate each view of multimedia content inindividual representations. In such examples, to output more than oneview, destination device 14 may request two or more representations ofthe multimedia content.

Operation point creation unit 114 may create operation points for one ormore representations of the multimedia content. In general, an operationpoint corresponds to a subset of views in a representation that aretargeted for output, where each of the views shares a common temporallevel. As defined by the H.264/AVC specification: An operation point isidentified by a temporal_id value representing the target temporal leveland a set of view_id values representing the target output views. Oneoperation point is associated with a bitstream subset, which consists ofthe target output views and all other views the target output viewsdepend on, that is derived using the sub-bitstream extraction process asspecified in subclause H.8.5.3 with tIdTarget equal to the temporal_idvalue and viewIdTargetList consisting of the set of view_id values asinputs. More than one operation point may be associated with the samebitstream subset. When the specification states “an operation point isdecoded” it refers to the decoding of a bitstream subset correspondingto the operation point and subsequent output of the target output views.

SEI message generation unit 108 may, in accordance with the techniquesdescribed in this disclosure, determine a nested supplementalinformation (SEI) message that applies to both texture and depthcomponents of a view component or only to a depth component of the viewcomponent. By enabling a nested SEI message to apply only to a depthcomponent, these aspects of the techniques may again promote separatehandling of texture and depth components.

SEI message generation unit 108 may perform these aspects of thetechniques to determine a supplemental enhancement information messagethat applies to coding of the view component of the multiview videodata. SEI message generation unit 108 may then determine a nestedsupplemental enhancement information message that applies in addition tothe supplemental enhancement information message when processes thedepth component of the view component. SEI message generation unit 108may then encode the depth component of the view component based on thesupplemental enhancement information message and the nested supplementalenhancement information message.

Typically, the nested SEI message includes a flag or other identifierthat indicates whether the nested SEI message applies to both thetexture and depth components of the view component or only to the depthcomponent. Thus, in some instances, SEI message generation unit 108 maydetermine that the nested supplemental enhancement information messageapplies in addition to the supplemental enhancement information messagewhen only processing the depth component of the view component andprocesses only the depth component of the view component and not thetexture component of the view component based on the supplementalenhancement information message and the nested supplemental enhancementinformation message. Alternatively, SEI message generation unit 108 maydetermine that the nested supplemental enhancement information messageapplies in addition to the supplemental enhancement information messagewhen processing the texture component of the view component and codesthe texture component of the view component based on the supplementalenhancement information message and the nested supplemental enhancementinformation message. Again, these aspects of the techniques againfacilitate separate handling or processing of depth and texturecomponents of the view component.

This flag may be defined for an SEI message referred to as a “3DVscalable nesting SEI message,” which may represent an SEI message fornesting of SEI messages for operation points containing depthcomponents. The following table illustrates an example 3DV scalablenesting SEI message syntax.

De- scrip- 3dv_scalable_nesting( payloadSize ) { C toroperation_point_flag 5 u(1) if ( !operation_point_flag ) {all_view_components_in_au_flag 5 u(1) if(!all_view_components_in_au_flag ) { num_view_components_minus1 5 ue(v)for( i = 0; i <= num_view_components_minus1; i++ ) { sei_view_id[ i ] 5u(10) sei_view_applicability_flag[ i ] 5 u(1) } } } else {num_view_components_op_minus1 5 ue(v) for( i = 0; i <=num_view_components_op_minus1; i++ ) { sei_op_view_id[ i ] 5 u(10)sei_op_view_applicability_flag[ i ] 5 u(1) } sei_op_temporal_id 5 u(3) }while( !byte_aligned( ) ) sei_nesting_zero_bit /* equal to 0 */ 5 f(1)sei_message( ) 5 }

In the table above, sei_view_applicability_flag[i] equal to 1 indicatesthat the nested SEI message applies to both the texture component andthe depth component of the view with view_id equal to sei_view_id[i].sei_view_applicability_flag[i] equal to 0 indicates that the nested SEImessage applies only to the depth component of the view with view_idequal to sei_view_id[i].

In the table above, sei_op_view_applicability_flag[i] equal to 1indicates that the nested SEI message applies to both the texturecomponent and the depth component of the view with view_id equal tosei_op_view_id[i]. sei_op_view_applicability_flag[i] equal to 0indicates that the nested SEI message applies only to the depthcomponent of the view with view_id equal to sei_op_view_id[i].

The semantics of the other syntax elements of 3DV scalable nesting SEImessage is the same as the semantics of the MVC scalable nesting SEImessage.

Alternatively, when a SEI message is nested for one view component, theSEI message may be nested for both the texture component and the depthcomponent of this view component. In this case, SEI message generationunit 108 defines the syntax of the 3DV scalable nesting SEI messagesimilar to the syntax of the MVC scalable nesting SEI message, and thesemantics of the 3DV scalable nesting SEI message similar to thesemantics of the MVC scalable nesting SEI message. In the semantics ofthe 3DV scalable nesting SEI message, as defined earlier, a viewcomponent may include (and may consist of) a texture component and adepth component. In the context of proposed Annex I, which may refer tothe 3DVC extension to H.264/AVC, the semantics of the MVC scalablenesting SEI message are changed as follows. The semantics of the MVCscalable nesting SEI message applies with all instances of “viewcomponents” being replaced by “texture components.” The following tablepresents the syntax of the MVC scalable nesting SEI message.

De- scrip- mvc_scalable_nesting( payloadSize ) { C toroperation_point_flag 5 u(1) if ( !operation_point_flag ) {all_view_components_in_au_flag 5 u(1) if(!all_view_components_in_au_flag ) { num_view_components_minus1 5 ue(v)for( i = 0; i <= num_view_components_minus1; i++ ) sei_view_id[ i ] 5u(10) } else { num_view_components_op_minus1 5 ue(v) for( i = 0; i <=num_view_components_op_minus1; i++ ) sei_op_view_id[ i ] 5 u(10)sei_op_temporal_id 5 u(3) } while( !byte_aligned( ) )sei_nesting_zero_bit /* equal to 0 */ 5 f(1) sei_message( ) 5 }

To further facilitate the separate handling of depth and texturecomponents, SEI message generation unit 108 may generate an SEI messagereferred to as a 3D view scalability SEI message that includes a firstsyntax element, a second syntax element, and a third syntax element,where the first syntax element indicates whether an operation pointcontains a depth component. When the operation point contains a depthcomponent, SEI message generation unit 108 may define the second syntaxelement to indicate a number of depth components on which a targetoutput view of the operation point directly depends and define the thirdsyntax elements to identify the depth components on which the targetoutput view of the operation point directly depends.

In some instances, the operation points may include a first subset ofthe operation points and a second subset of the operation points, whereeach operation point in the first subset contains only a texturecomponent and each operation point in the second subset contains a depthcomponent. SEI message generation unit 108 may then determine that aprofile identifier is equal to a given value that is associated with 3Dvideo coding and generate, in response to determining that the profileidentifier is equal to the given value, a subset SPS such that thesubset SPS includes a first SPS extension and a second SPS extension.The first SPS extension may indicate the first subset and the levels towhich the operation points in the first subset belong. The second SPSextension may indicate the second subset and the levels to whichoperation points in the second subset belong. In this way, thetechniques may permit operations points to be defined separately fortexture and depth components and by level.

In this manner, a video coding device may determine first sequence levelinformation describing characteristics of the depth components anddetermining second sequence level information describing characteristicsof an operation point of the video data. In some examples, the firstsequence level information comprises a three-dimensional video codingsequence parameter set that specifies a view dependency of the depthcomponents. Moreover, the video coding device may determining areference picture list that identifies one or more reference picturesfor the depth components indicated in the three-dimensional video codingsequence parameter set.

In some examples, the second sequence level information includes athree-dimensional video coding sequence parameter set that described,for the operation point, a list of target output views, a number oftexture views to be decoded when decoding the operation point, and anumber of depth views to be decoded for when decoding the operationpoint, where the number of texture views to be decoded is different formthe number of depth views. In some examples, the video coding device mayfurther target, for each of the target output views specified in thelist of target output views, the one or more depth components whenavailable.

In some examples, the video coding device may specify athree-dimensional video coding scalability information SEI message aspart of the video data, wherein three-dimensional video codingscalability information SEI message includes a description of theoperation point without the depth components or a description of theoperation point with the depth components. In some instances, the SEImessage includes an indication of whether the operation point includesthe depth components. Moreover, in some examples, the SEI messageincludes an indication of whether the operation point includes the depthcomponents and directly dependent depth views with directly dependenttexture views for the decoding of the operation point.

This aspect of the techniques may leverage the separate handling ofdepth and texture components to permit operation points to be moreeasily extracted from a bitstream for multiview video coding. Bysignaling whether an operation point includes depth, a video decoder,such as video decoder 30, may determine which operation point bestaccommodates the abilities of video decoder 30. For example, videodecoder 30 may be optimized to perform multiview video coding usingviews that do not include depth, preferring multiview video data whereboth the left and right eye perspectives are provided as separatepictures. Video decoder 30 may alternatively be optimized fordepth-based multiview video data but may only accommodate a single viewrather than two or more views. By signaling when the encoded multiviewvideo data includes depth, and when including depth, the number of depthcomponents on which the target output views of the operation pointdirectly depends, video decoder 30 may select an operation point thataccommodates the capabilities or optimizations of video decoder 30.

In operation, a 3D view scalability information SEI message, in oneexample, may have syntax elements specified as shown in the followingtable.

3d_view_scalability_info( payloadSize ) { C Descriptornum_operation_points_minus1 5 ue(v) for( i = 0; i <=num_operation_points_minus1; i++ ) { operation_point_id[ i ] 5 ue(v)priority_id[ i ] 5 u(5) temporal_id[ i ] 5 u(3)num_target_output_views_minus1[ i ] 5 ue(v) op_with_depth_flag[ i ] for(j = 0; j <= num_target_output_views_minus1[ i ]; j++ ) view_id[ i ][ j ]5 ue(v) profile_level_info_present_flag[ i ] 5 u(1)bitrate_info_present_flag[ i ] 5 u(1) frm_rate_info_present_flag[ i ] 5u(1) if( !num_target_output_views_minus1[ i ] )view_dependency_info_present_flag[ i ] 5 u(1)parameter_sets_info_present_flag[ i ] 5 u(1)bitstream_restriction_info_present_flag[ i ] 5 u(1) if (profile_level_info_present_flag[ i ] ) op_profile_level_idc[ i ] 5 u(24)if( bitrate_info_present_flag[ i ] ) { avg_bitrate[ i ] 5 u(16)max_bitrate[ i ] 5 u(16) max_bitrate_calc_window[ i ] 5 u(16) } if(frm_rate_info_present_flag[ i ] ) { constant_frm_rate_idc[ i ] 5 u(2)avg_frm_rate[ i ] 5 u(16) } if( view_dependency_info_present_flag[ i ] ){ num_directly_dependent_views[ i ] 5 ue(v) for( j = 0; j <num_directly_dependent_views[ i ]; j++ ) { directly_dependent_view_id[ i][ j ] 5 ue(v) if(op_with_depth_flag[ i ]) {num_directly_dependent_depth_views[ i ] for( j = 0; j <num_directly_dependent_views[ i ]; j++ ) {directly_dependent_depth_view_id[ i ][ j ] 5 ue(v) } } elseview_dependency_info_src_op_id[ i ] 5 ue(v) if(parameter_sets_info_present_flag[ i ] ) {num_seq_parameter_set_minus1[i] 5 ue(v) for( j = 0; j <=num_seq_parameter_set_minus1[ i ]; j++ ) seq_parameter_set_id_delta[ i][ j ] 5 ue(v) num_subset_seq_parameter_set_minus1[ i ] 5 ue(v) for( j =0; j <= num_subset_seq_parameter_set_minus1[i]; j++ )subset_seq_parameter_set_id_delta[ i ][ j ] 5 ue(v)num_pic_parameter_set_minus1[ i ] 5 ue(v) for( j = 0; j <=num_init_pic_parameter_set_minus1[ i ]; j++ )pic_parameter_set_id_delta[ i ][ j ] 5 ue(v) } elseparameter_sets_info_src_op_id[ i ] 5 ue(v) if(bitstream_restriction_info_present_flag[ i ] ) {motion_vectors_over_pic_boundaries_flag[ i ] 5 u(1)max_bytes_per_pic_denom[ i ] 5 ue(v) max_bits_per_mb_denom[ i ] 5 ue(v)log2_max_mv_length_horizontal[ i ] 5 ue(v) log2_max_mv_length_vertical[i ] 5 ue(v) num_reorder_frames[ i ] 5 ue(v) max_dec_frame_buffering[ i ]5 ue(v) } } }

Alternatively, 3D view scalability information SEI messages may havesyntax elements as defined in the following table.

De- scrip- 3d_view_scalability_info( payloadSize ) { C tor //same syntaxelements as in view_scalability_info( ) for( i = 0; i <=num_operation_points_minus1; i++ ) { op_with_depth_flag[ i ] 5 u(1) if(view_dependency_info_present_flag[ i ] && op_with_depth_flag[ i ]) {num_directly_dependent_depth_views[ i ] for( j = 0; j <num_directly_dependent_views[ i ]; j++ ) {directly_dependent_depth_view_id[ i ][ 5 ue(v) j ] } } }

The semantics of the other syntax elements of 3DV view scalabilitymessage is the same as the semantics of the MVC view scalabilityinformation SEI message. The syntax elements in the view scalabilityinformation SEI have the same semantics as in Annex H, but apply tooperation points that may potentially contain depth components.

In the tables above, op_with_depth_flag[i] equal to 1 indicates that thecurrent operation point contains depth views. op_with_depth_flag[i]equal to 0 indicates that the current operation point does not containany depth views. num_directly_dependent_views[i] anddirectly_dependent_view_id[i][j] apply only to texture components of anoperation point if the operation point contains both texture and depth(op_with_depth_flag[i] equal to 0). Alternatively, the names of the twosyntax elements are changed to num_directly_dependent_texture sei_opviews[i] and directly_dependent_texture_view_id[i][j], respectively,with the same semantics as above. The semantics of the other syntaxelements of 3DV view scalability message are the same as the semanticsof the MVC view scalability information SEI message.

In the tables above, num_directly_dependent_depth_views[i] specifies thenumber of depth views that the target output view of the currentoperation point is directly dependent on within the representation ofthe current operation point. The value ofnum_directly_dependent_depth_views[i] shall be in the range of 0 to 16,inclusive.

In the tables above, directly_dependent_depth_view sei_op id[i][j]specifies the view_id of the j-th depth view that the depth view of thetarget output view of the current operation point is directly dependenton within the representation of the current operation point. The valueof directly_dependent_depth_view_id[i][j] shall be in the range of 0 to1023, inclusive.

In other examples, depth only operation points may be signaled in thisSEI message and thus an indication op_texture_depth_idc[i] is added, asshown in the following table.

De- scrip- 3d_view_scalability_info( payloadSize ) { C torview_scalability_info( payloadSize ) for( i = 0; i <=num_operation_points_minus1; i++ ) { op_texture_depth_idc[ i ] 5 ue(v)if( view_dependency_info_present_flag[ i ] && op_with_depth_flag[ i ]== 1) { num_directly_dependent_depth_views[ i ] for( j = 0; j <num_directly_dependent_views[ i ]; j++ ) {directly_dependent_depth_view_id[ i ][ 5 ue(v) j ] } } }

In the table above, op_texture_depth_idc[i] equal to 0 indicates thatthe current operation points contain only texture components. Theop_texture_depth_idc[i] syntax element equal to 1 indicates that thecurrent operation point contains both texture components and depthcomponents. The op_texture_depth_idc[i] syntax element equal to 2indicates that the current operation point contains only depthcomponents. Num_directly_dependent_views[i] anddirectly_dependent_view_id[i][j] apply only to texture components of anoperation point if the operation point contains texture(op_texture_depth_idc[i] equal to 0 or 1).Num_directly_dependent_views[i] and directly_dependent_view_id[i][j]apply only to depth components of an operation point if the operationpoint contains only texture (op_texture_depth_idc[i] equal to 2).

In some examples, in accordance with the techniques of the disclosure, avideo encoder may generate a SEI message that includes a first syntaxelement, a second syntax element, and third syntax elements. The firstsyntax element indicates whether an operation point contains a depthcomponent. If the operation point contains a depth view, the secondsyntax element indicates a number of depth components on which a targetoutput view of the operation point directly depends, and the thirdsyntax elements identify the depth components on which the target outputview of the operation point directly depends. A video encoder may encodethe depth components.

In some such examples, the video encoder may generate the SEI messagesuch that the SEI message includes a fourth syntax element and fifthsyntax elements. If the operation point has both texture and depthcomponents, the fourth syntax element indicates how many texturecomponents are associated with the operation point and the fifth syntaxelements identify the texture components on which the target output viewof the operation point directly depends.

Alternatively, the video encoder may signal depth-only operation pointsin the SEI message. For instance, the video encoder may generate the SEImessage such that the first syntax element indicates whether theoperation point contains only texture components, contains both texturecomponents and depth components, or contains only depth components.

Furthermore, in some examples, the techniques of this disclosure mayprovide a video decoder that receives a SEI message that includes afirst syntax element, a second syntax element, and third syntaxelements. The first syntax element indicates whether an operation pointcontains a depth component. If the operation point contains a depthview, the second syntax element indicates a number of depth componentson which a target output view of the operation point directly depends,and the third syntax elements identifies the depth components on whichthe target output view of the operation point directly depends. Thevideo decoder may decode the depth components.

Furthermore, the SEI message may include a fourth syntax element andfifth syntax elements. If the operation point has both texture and depthcomponents, the fourth syntax element indicates how many texturecomponents are associated with the operation point and the fifth syntaxelements identify the texture components on which the target output viewof the operation point directly depends.

Alternatively, the SEI message may signal depth-only operation points inthe SEI message. For instance, the first syntax element may indicatewhether the operation point contains only texture components, containsboth texture components and depth components, or contains only depthcomponents.

With respect to operation points and adapting or modifying operationpoints to potentially provide for separate handling of texture and depthcomponents, various aspects of the techniques described in thisdisclosure may provide for signaling of levels of operation pointscontaining depth components in four different ways: 1) reusing the SPSsyntax elements, 2) using similar syntax elements in 3DVC SPS extension,3) adding more syntax elements in 3DVC SPS extension, and 4) using analternate set of more syntax elements in 3DVC SPS extension.

With respect to the first way, i.e., reusing the SPS syntax elements,level definitions syntax elements in the MVC SPS extension are used toindicate the operation points containing depth components. Eachoperation point signaled in the MVC SPS extension as part of the subsetSPS contains a profile_idc belonging to one of the 3D video profiles.Each operation point specifies a number of output views, each of whichcontains both a texture component and a depth component. Operation pointcreation unit 114 may implement this first way to facilitate separatehandling of depth and texture components.

With respect to the second way, i.e., using similar syntax elements in3DV SPS extension, the level definitions syntax elements in MVC SPSextension may still be used to indicate the operation points containingonly texture components. In a 3DVC SPS extension of the subset SPS,similar level definitions are added, indicating the operation pointscontaining depth components. Operation point creation unit 114 mayimplement this second way to facilitate separate handling of depth andtexture components. The following syntax tables illustrate the similarsyntax elements.

subset_seq_parameter_set_rbsp( ) { C Descriptor seq_parameter_set_data() 0 if( profile_idc = = 83 | | profile_idc = = 86 ) {seq_parameter_set_svc_extension( ) /* specified in Annex G 0 */svc_vui_parameters_present_flag 0 u(1) if(svc_vui_parameters_present_flag = = 1 ) svc_vui_parameters_extension( )/* specified in Annex G 0 */ } else if( profile_idc = = 118 | |profile_idc = = 128 ) { bit_equal_to_one /* equal to 1 */ 0 f(1)seq_parameter_set_mvc_extension( ) /* specified in 0 Annex H */mvc_vui_parameters_present_flag 0 u(1) if(mvc_vui_parameters_present_flag = = 1 ) mvc_vui_parameters_extension( )/* specified in Annex H 0 */ } else if ( profile_idc = = 138) {bit_equal_to_one /* equal to 1 */ 0 f(1)seq_parameter_set_mvc_extension( ) mvc_vui_parameters_present_flag 0u(1) if( mvc_vui_parameters_present_flag = = 1 )mvc_vui_parameters_extension( ) /* specified in Annex H 0 */seq_parameter_set_3dv_extension( ) . . . } } additional_extension3_flag0 u(1) if ( additional_extension3_flag ) while( more_rbsp_data( ) )additional_extension3_data_flag 0 u(1) } rbsp_trailing_bits( ) 0 }

seq_parameter_set_3dv_extension( ) { C Descriptor for( i = 0; i <=num_level_values_signalled_minus1; i++ )num_level_values_signalled_minus1 0 ue(v) for( i = 0; i <=num_level_values_signalled_minus1; i++ ) { level_idc[ i ] 0 u(8)num_applicable_ops_minus1[ i ] 0 ue(v) for( j = 0; j <=num_applicable_ops_minus1[ i ]; j++ ) { applicable_op_temporal_id[ i ][j ] 0 u(3) applicable_op_num_target_views_minus1[ i ][ j ] 0 ue(v) for(k = 0; k <= applicable_op_num_target_views_minus1[ i ][ j ]; k++ )applicable_op_target_view_id[ i ][ j ][ k ] 0 ue(v)applicable_op_num_views_minus1[ i ][ j ] 0 ue(v) } } . . . }

In the above syntax table, each operation point hasnum_sei_op_target_views_minus1[i][j]+1 views, each of which containsboth a texture component and a depth component. So, the semantics of thesyntax elements are the same as those in the SPS MVC extension exceptthat each view contains both a texture component and a depth component,or equivalently, each view component contains both a texture componentand a depth component.

With respect to the third way, i.e., adding more syntax elements in 3DVSPS extension, the 3DV SPS extension may add more operation pointscontaining texture components that need to be signaled on top of theoperation points signaled in the MVC SPS extension. In this case,operation point creation unit 114 may add an additional flag to indicatewhether the current operation point contains a depth component or not,as shown in the following syntax table.

seq_parameter_set_3dvc_extension( ) { C Descriptor for( i = 0; i <=num_level_values_signalled_minus1; i++ )num_level_values_signalled_minus1 0 ue(v) for( i = 0; i <=num_level_values_signalled_minus1; i++ ) { level_idc[ i ] 0 u(8)num_applicable_ops_minus1[ i ] 0 ue(v) for( j = 0; j <=num_applicable_ops_minus1[ i ]; j++ ) { applicable_op_temporal_id[ i ][j ] 0 u(3) applicable_op_num_target_views_minus1[ i ][ j ] 0 ue(v)applicable_op_with_depth_flag[ i ][ j ] 0 u(1) for( k = 0; k <=applicable_op_num_target_views_minus1[ i ][ j ]; k++ )applicable_op_target_view_id[ i ][ j ][ k ] 0 ue(v)applicable_op_num_views_minus1[ i ][ j ] 0 ue(v) } } . . . }

In the table above, applicable_op_with_depth_flag[i][j] equal to 1indicates that in the current operation point (identified by i and j),each target output view contains both a texture component and a depthcomponent, this flag equal to 0 indicates that in the current operationpoint contains only texture for each target output view. The semanticsof the other syntax elements of the 3DVC scalable nesting SEI messageare the same as the semantics of the MVC scalable nesting SEI message.

With respect to the fourth way, i.e., using an alternate set of moresyntax elements in 3DV SPS extension, there might be depth onlyoperation points. In this instance, operation point creation unit 114may add a 2-bit indication to signal three different cases for eachoperation point: texture only, depth only and both texture and depth.The following table illustrates these new syntax elements to be added tothe SPS 3DVC extension:

seq_parameter_set_3dvc_extension( ) { C Descriptor for( i = 0; i <=num_level_values_signalled_minus1; i++ )num_level_values_signalled_minus1 0 ue(v) for( i = 0; i <=num_level_values_signalled_minus1; i++ ) { level_idc[ i ] 0 u(8)num_applicable_ops_minus1[i] 0 ue(v) for( j = 0; j <=num_applicable_ops_minus1[ i ]; j++ ) { applicable_op_temporal_id[ i ][j ] 0 u(3) applicable_op_num_target_views_minus1[ i ][ j ] 0 ue(v)applicable_op_with_texture_depth_idc[ i ][ j ] 0 u(2) for( k = 0; k <=applicable_op_num_target_views_minus1[ i ][ j ]; k++ )applicable_op_target_view_id[ i ][ j ][ k ] 0 ue(v)applicable_op_num_views_minus1[ i ][ j ] 0 ue(v) } } . . . }

In the table above, applicable_op_with_texture_depth_idc[i][j] equal to0 indicates that in the current operation point (identified by i and j),each target output view contains both a texture component and a depthcomponent, applicable_op_with_texture_depth_idc[i][j] equal to 1indicates that the current operation point contains only texture foreach target output view, applicable_op_with_texture_depth_idc[i][j]equal to 2 indicates that the current operation point contains onlydepth for each target output view. Alternatively,applicable_op_with_texture_depth_idc[i][j] can be coded as ue(v).

In some instances, for a 3DV operation point, two different viewdependencies may be signaled in, e.g., an active texture MVC SPS and anactive view MVC SPS because the depth views may have differentinter-view dependencies. One example is that there might be nointer-view dependency at all for depth. In this case the semantics ofapplicable_op_num_views_minus 1 [i][j] is not clear. In the context ofMVC, applicable_op_num_views_minus1[i][j] specifies the number of viewsto be decoded for a specific operation point.

In some examples, the same view dependency can be assumed for textureand depth. If view dependencies of texture and depth are the same, thesemantics of this syntax element (i.e.,applicable_op_num_views_minus1[i][j]) can be kept aligned to the numberof views to be decoded, however, it is implied that each view containstexture and depth.

In some examples, accurate numbers of views to be decoded for bothtexture and depth are signaled. The following table illustrates syntaxelements of a sequence parameter set 3DVC extension that incorporatesthis aspect of the techniques:

seq_parameter_set_3dvc_extension( ) { C Descriptor for( i = 0; i <=num_level_values_signalled_minus1; i++ )num_level_values_signalled_minus1 0 ue(v) for( i = 0; i <=num_level_values_signalled_minus1; i++ ) { level_idc[ i ] 0 u(8)num_applicable_ops_minus1[ i ] 0 ue(v) for( j = 0; j <=num_applicable_ops_minus1[ i ]; j++ ) { applicable_op_temporal_id[ i ][j ] 0 u(3) applicable_op_num_target_views_minus1[ i ][ j ] 0 ue(v) for(k = 0; k <= applicable_op_num_target_views_minus1[ i ][ j ]; k++ )applicable_op_target_view_id[ i ][ j ][ k ] 0 ue(v)applicable_op_num_views_minus1[ i ][ j ] 0 ue(v)applicable_op_num_views_depth_minus1[ i ][ j ] 0 ue(v) } } . . . }

In the table above, applicable_op_num_views_minus1[i][j] plus 1specifies the number of texture views required for decoding the targetoutput views corresponding to the j-th operation point to which thelevel indicated by level_idc[i] applies.Applicable_op_num_views_depth_minus1[i][j] plus 1 specifies the numberof depth views required for decoding the target output viewscorresponding to the j-th operation point to which the level indicatedby level_idc[i] applies. Alternatively,applicable_op_num_views_depth_minus1[i][j] is not added but thesemantics of applicable_op_num_views_minus1[i][j] is changed.Applicable_op_num_views_minus1[i][j] plus 1 specifies the number oftexture views plus the number of depth views required for decoding thetarget output views corresponding to the j-th operation point to whichthe level indicated by level_idc[i] applies.

In some instances, the techniques of this disclosure provide forsignaling, in a sequence parameter set, a number of texture views to bedecoded for an operation point and a number of depth views to be decodedfor the operation point. Signaling the number of texture views and thenumber of depth views may comprise generating, in the sequence parameterset, a syntax element that indicates a number of views to be decoded forthe operation point, each of the views having one of the texture viewsand one of the depth views. Signaling the number of texture views andthe number of depth views may comprise generating, in the sequenceparameter set, a first syntax element and a second syntax element, thefirst syntax element specifying the number of texture views to bedecoded for the operation point, and the second syntax elementspecifying the number of depth views to be decoded for the operationpoint. Signaling the number of texture views and the number of depthviews may comprise generating, in the sequence parameter set, a syntaxelement that indicates the number of texture views to be decoded for theoperation point plus the number of depth views to be decoded for theoperation point.

In some examples, the techniques of this disclosure may provide forreceiving a sequence parameter set that signals a number of textureviews to be decoded for an operation point and a number of depth viewsto be decoded for the operation point. In such examples, the sequenceparameter set may include a syntax element that indicates a number ofviews to be decoded for the operation point, each of the views havingone of the texture views and one of the depth views. The sequenceparameter set may include a first syntax element and a second syntaxelement, the first syntax element specifying the number of texture viewsto be decoded for the operation point, and the second syntax elementspecifying the number of depth views to be decoded for the operationpoint. The sequence parameter set may include a syntax element thatindicates the number of texture views to be decoded for the operationpoint plus the number of depth views to be decoded for the operationpoint.

While various aspects of the techniques are described above as beingperformed by encapsulation unit 21, the techniques may be performed in asame or reciprocal manner by decapsulation unit 29. Moreover, variousaspects of the techniques described above as being performed byencapsulation unit 21 may also, in other implementations, be performedby video encoder 20 (with video decoder 30 performing same or reciprocaloperations as those being performed by video encoder 20). Thus, while aparticular implementation is shown in the examples of FIG. 1-3, thetechniques should not be limited to this example, but may apply to otherimplementations that provide for separate handling of texture and depthcomponents of a view component specified by multiview video data.

FIG. 5 is a conceptual diagram illustrating an example MVC predictionpattern. The following description of MVC again relates to 3DVC in thesense that 3DVC incorporates MVC plus depth. Accordingly, thedescription of MVC and the various predictions provided by MVC aredescribed to provide context for understanding 3DVC and the techniquesdescribed in this disclosure that relate to 3DVC.

In the example of FIG. 5, eight views are illustrated, and twelvetemporal locations are illustrated for each view. In general, each rowin FIG. 5 corresponds to a view, while each column indicates a temporallocation. Each of the views may be identified using a view identifier(“view_id”), which may be used to indicate a relative camera locationwith respect to the other views. In the example shown in FIG. 5, theview IDs are indicated as “S0” through “S7,” although numeric view IDsmay also be used. In addition, each of the temporal locations may beidentified using a picture order count (POC) value, which indicates adisplay order of the pictures. In the example shown in FIG. 4, the POCvalues are indicated as “T0” through “T11.”

Although MVC has a so-called base view which is decodable by H.264/AVCdecoders and stereo view pair can be supported by MVC, MVC may supportmore than two views as a 3D video input. Accordingly, a renderer of aclient having an MVC decoder may expect 3D video content with multipleviews.

Pictures in FIG. 5 are indicated using a shaded block including aletter, designating whether the corresponding picture is intra-coded(that is, an I-frame), or inter-coded in one direction (that is, as aP-frame) or in multiple directions (that is, as a B-frame). In general,predictions are indicated by arrows, where the pointed-to picture usesthe point-from object for prediction reference. For example, the P-frameof view S2 at temporal location TO is predicted from the I-frame of viewS0 at temporal location T0. Each of the pictures shown in FIG. 5 may bereferred to as a view component.

As with single view video encoding, pictures of a multiview videosequence may be predictively encoded with respect to pictures atdifferent temporal locations. For example, the b-frame of view S0 attemporal location T1 has an arrow pointed to it from the I-frame of viewS0 at temporal location T0, indicating that the b-frame is predictedfrom the I-frame. Additionally, however, in the context of multiviewvideo encoding, pictures may be inter-view predicted. That is, a viewcomponent can use the view components in other views for reference. InMVC, for example, inter-view prediction is realized as if the viewcomponent in another view is an inter-prediction reference. Thepotential inter-view references may be signaled in the SPS MVC extensionand may be modified by the reference picture list construction process,which enables flexible ordering of the inter-prediction or inter-viewprediction references.

FIG. 5 provides various examples of inter-view prediction. Pictures ofview S1, in the example of FIG. 5, are illustrated as being predictedfrom pictures at different temporal locations of view S1, as well asinter-view predicted from pictures of pictures of views S0 and S2 at thesame temporal locations. For example, the b-frame of view S1 at temporallocation T1 is predicted from each of the B-frames of view S1 attemporal locations T0 and T2, as well as the b-frames of views S0 and S2at temporal location T1.

In the example of FIG. 5, capital “B” and lowercase “b” are intended toindicate different hierarchical relationships between pictures, ratherthan different encoding methodologies. In general, capital “B” framesare relatively higher in the prediction hierarchy than lowercase “b”frames. FIG. 5 also illustrates variations in the prediction hierarchyusing different levels of shading, where a greater amount of shading(that is, relatively darker) pictures are higher in the predictionhierarchy than those pictures having less shading (that is, relativelylighter). For example, all I-frames in FIG. 5 are illustrated with fullshading, while P-frames have a somewhat lighter shading, and B-frames(and lowercase b-frames) have various levels of shading relative to eachother, but always lighter than the shading of the P-frames and theI-frames.

In general, the prediction hierarchy is related to view order indexes,in that pictures relatively higher in the prediction hierarchy should bedecoded before decoding pictures that are relatively lower in thehierarchy, such that those pictures relatively higher in the hierarchycan be used as reference pictures during decoding of the picturesrelatively lower in the hierarchy. A view order index is an index thatindicates the decoding order of view components in an access unit. Theview order indices may be implied in a parameter set, such as an SPS.

In this manner, pictures used as reference pictures may be decodedbefore decoding the pictures that are encoded with reference to thereference pictures. A view order index is an index that indicates thedecoding order of view components in an access unit. According toMVC/AVC, for each view order index i, the corresponding view_id issignaled. The decoding of the view components follows the ascendingorder of the view order indexes. If all the views are presented, thenthe set of view order indexes comprises a consecutively ordered set fromzero to one less than the full number of views.

In some instances, a subset of a whole bitstream can be extracted toform a sub-bitstream which still conforms to MVC. There are manypossible sub-bitstreams that specific applications may require, basedon, for example, a service provided by a server, the capacity, support,and capabilities of decoders of one or more clients, and/or thepreference of one or more clients. For example, a client might requireonly three views, and there might be two scenarios. In one example, oneclient may require a smooth viewing experience and might prefer viewswith view_id values S0, S1, and S2, while another other client mayrequire view scalability and prefer views with view_id values S0, S2,and S4. Both of these sub-bitstreams can be decoded as independent MVCbitstreams and can be supported simultaneously.

While FIG. 5 shows eight views (S0-S7), as noted above, the MVC/AVCextension supports up to 1024 views and uses a view_id in a NAL unitheader to identify the view to which a NAL unit belongs. A view orderindex may be signaled as part of a NAL unit header. That is, forpurposes of comparison, a view order index may replace the view_id thatis signaled in the NAL unit header of the MVC/AVC extension. View ordergenerally describes the ordering of the views in an access unit, and aview order index identifies a particular view in view order of theaccess unit. That is, a view order index describes the decoding order ofa corresponding view component of an access unit.

Accordingly, an SPS may provide a relationship between view_ids for theviews and view order indexes for the views. Using the view order indexand the data in the SPS, video encoder 20 and video decoder 30 mayreplace the 10 bit view_id of MVC/AVC in the NAL unit header by the vieworder index, which may lead to a bit savings over the MVC/AVC scheme.

An example SPS that provides a relationship between view_ids for theviews and view order indexes is provided in the table below:

SEQUENCE PARAMETER SET MVC EXTENSION seq_parameter_set_mvc_extension( ){ C Descriptor num_views_minus1 0 ue(v) for( i = 0; i <=num_views_minus1; i++ ) { view_id[ i ] 0 ue(v) view_level[ i ] 0 ue(v) }for( i = 1; i <= num_views_minus1; i++ ) { num_ref_views[ i ] 0 ue(v)for( j = 0; j < num_ref_views[ i ]; j++ ) ref_view_idx[ i ][ j ] 0 ue(v)} num_level_values_signalled_minus1 0 ue(v) for( i = 0; i <=num_level_values_signalled_minus1; i++ ) { level_idc[ i ] 0 u(8)num_applicable_ops_minus1[i] 0 ue(v) for( j = 0; j <=num_applicable_ops_minus1[ i ]; j++ ) { applicable_op_temporal_id[ i ][j ] 0 u(3) applicable_op_num_target_views_minus1[ i ][ j ] 0 ue(v) for(k = 0; k <= applicable_op_num_target_views_minus1[ i ][ j ]; k++ )applicable_op_target_view_idx[ i ][ j ][ k ] 0 ue(v)applicable_op_num_views_minus1[ i ][ j ] 0 ue(v) } } }

The SPS shown in the above Table specifies inter-view dependencyrelationships for a coded video sequence. The SPS also specifies levelvalues for a subset of the operation points for the coded videosequence. All SPSs that are referred to by a coded video sequence shouldbe identical. However, some views identified by view_id[i] may not bepresent in the coded video sequence. In addition, some views or temporalsubsets described by the SPS may have been removed from the originalcoded video sequence, and thus may not be present in the coded videosequence. The information in the SPS, however, may always apply to theremaining views and temporal subsets.

In the above table, the num_views_minus1 plus 1 syntax element specifiesthe maximum number of coded views in the coded video sequence. The valueof num_view_minus1 may be in the range of 0 to 31, inclusive. In someinstances, the actual number of views in the coded video sequence may beless than num_views_minus1 plus 1. The view_id[i] element specifies theview identifier of the view with a view order index equal to i. Theview_level[i] element specifies the view_level of the view with a vieworder index equal to i. In some examples, all view components with aview_level up to a predefined value (VL) may be decodable withoutdecoding any view component with a view_level larger than VL.

The num_ref_views[i] element specifies the number of view components forinter-view prediction in the initial reference picture list RefPicList0and RefPicList1 when decoding view components with view order indexequal to i. The value of the num_ref_views[i] element may not be greaterthan Min(15, num_views_minus1). The value of num_ref_views[0] may beequal to 0. In addition, the ref_view_idx[i][j] element may specify theview order index of the j-th view component for inter-view prediction inthe initial reference picture list RefPicList0 and RefPicList1 whendecoding a view component with view order index equal to i. The value ofref_view_idx[i][j] may be in the range of 0 to 31, inclusive.

FIG. 6 is a flow diagram illustrating operation of a video coding devicein implementing parameter set activation in accordance with variousaspects of the techniques described in this disclosure. Initially, avideo coding device, such as video decoder 30, may determine an orderindex value assigned to a view component of multiview video data (130).This order index value is described above in more detail with respect toFIG. 5. As described above, video decoder 30 may then activate aparameter set as a texture parameter set for the texture component ofthe view component based at least on the determined view order indexvalue assigned to the view component of the multiview video data (132).After activating this texture parameter set, video encoder 30 may thencode the texture component of the view component based on the activatedtexture parameter set (134).

In some instances, video decoder 30 codes only the texture component ofthe view component and not the depth component of the view componentbased on the activated texture parameter set. In some instances, videodecoder 30 activates another parameter set for the depth component ofthe view component based at least on the view order index value assignedto the view component of the multiview video data and decodes the depthcomponent of the view component based on the parameter set activated forthe depth component of the view component and not the activated textureparameter set in the manner described above. Thus, while not explicitlyshown in the example of FIG. 6, additional parameter sets may beindividually activated for the depth component, which video decoder 30may then use to decode the depth component but not the texturecomponent.

In some of the above described instances, video decoder 30 may activatea sequence parameter set for coding the view component of the multiviewvideo data based at least on the view order index value assigned to theview component of the multiview video data. Moreover, as noted above,video decoder 30 may activate a sequence parameter set as the texturesequence parameter set for the texture component of the view componentbased at least on the view order index value assigned to the viewcomponent of the multiview video data such that one or more syntaxelements specified by the texture sequence parameter set either overrideor augment one or more syntax elements specified by the activatedsequence parameter set.

In some of the above described examples, video decoder 30 may activate apicture parameter set as the texture picture parameter set for thetexture component of the view component based at least on the view orderindex value assigned to the view component of the multiview video datasuch that one or more syntax elements specified by the texture pictureparameter set either override or augment one or more syntax elementsspecified by the activated sequence parameter set.

In some of the above described examples, video decoder 30 may activate apicture parameter set as a view picture parameter set for the viewcomponent of the multiview video data based at least on the view orderindex value assigned to the view component of the multiview video data.Additionally, video decoder 30 may then activate the parameter set asthe texture parameter set by activating a picture parameter set as thetexture picture parameter set for the texture component of the viewcomponent based at least on the view order index value assigned to theview component of the multiview video data such that one or more syntaxelements specified by the texture picture parameter set either overrideor augment one or more syntax elements specified by the activated viewpicture parameter set.

In some examples, video decoder 30 may then activate the parameter setas the texture parameter set by activating one or more of a sequenceparameter set and a picture parameter as a texture sequence parameterset and a texture picture parameter set, respectively, for the texturecomponent of the view component based at least on the view order indexvalue assigned to the view component of the multiview video data.

It should also be understood that the steps shown and described withrespect to FIG. 6 are provided as merely one example. That is, the stepsshown in the example of FIG. 6 need not necessarily be performed in theorder shown in FIG. 6, and fewer, additional, or alternative steps maybe performed. Moreover, while the techniques are described above withrespect to a particular video coder, i.e., video decoder 30, thetechniques may be implemented by any video coder, including videoencoder 20.

FIG. 7 is a flow diagram illustrating example operation of processingmultiview video data to generate nested SEI messages in accordance withthe techniques described in this disclosure. While described withrespect to a particular unit below, i.e., encapsulation unit 21, thetechniques may generally be implemented by any video coding device,including destination device 14 and more particularly decapsulation unit29 of destination device 14.

Initially, encapsulation unit 21 receives encoded multiview video dataand invokes SEI message generation unit 108, which determines asupplemental enhancement information (SEI) message that applies whenprocessing the view component of the multiview video data in the mannerdescribed above (140). SEI message generation unit 108 may, as describedabove, also determine whether a nested SEI message applies to bothtexture and depth components of the view component or only to the depthcomponent of the view component (141). Upon determining that the nestedSEI message applies only to the depth component (“NO” 141), SEI messagegeneration unit 108 may determine a nested supplemental enhancementinformation message that applies only to the depth component of the viewcomponent in addition to the supplemental enhancement informationmessage (142). However, upon determining that the nested SEI messageapplies to both the depth and texture components (“YES” 141), SEImessage generation unit 108 may determine a nested supplementalenhancement information message that applies both to the texturecomponent and the depth component of the view component in addition tothe supplemental enhancement information message (143). Video filecreation unit 104 may then generate a video file that includes both theSEI message and the nested SEI message (144).

In some instances, encapsulation unit 21 generates this video file andprovides this video file to router 36 or another device, such as a videoserver of content delivery network 34 (both of which are described abovewith respect to the example of FIG. 1). This device may then process thedepth component of the view component based on the supplementalenhancement information message and the nested supplemental enhancementinformation message.

In some examples, encapsulation unit 21 determines the nestedsupplemental enhancement information message that applies in addition tothe parent supplemental enhancement information message when only codingthe depth component of the view component. Router 36 in this instancemay then process only the depth component of the view component and notthe texture component of the view component based on the parentsupplemental enhancement information message and the nested supplementalenhancement information message.

As noted above, encapsulation unit 21 may determine whether the nestedsupplemental enhancement information message applies in addition to thesupplemental enhancement information message when coding the texturecomponent of the view component. As a result, router 36 may, in thisinstance, process the texture component of the view component based onthe supplemental enhancement information message and the nestedsupplemental enhancement information message based on the determinationof whether the nested supplemental enhancement information messageapplies in addition to the supplemental enhancement information messagewhen coding the texture component of the view component.

When determining that the nested supplemental enhancement messageapplies in addition to the supplemental enhancement information messagewhen processing the texture component of the view component, router 36may identify a flag in the nested supplemental enhancement informationmessage that specifies whether or not the nested supplementalenhancement information message applies only to the depth component orto both the view component and the depth component and determine thatthe nested supplemental enhancement message applies in addition to thesupplemental enhancement information message when coding the texturecomponent of the view component based on the identified flag. The flagmay comprise one or more of a supplemental enhancement information viewapplicability flag and a supplemental enhancement informationoperational view applicability flag.

In some instances, when determining whether the nested supplementalenhancement information message applies in addition to the supplementalenhancement information message when processing the texture component ofthe view component, router 36 may determine that the nested supplementalenhancement information message applies, in addition to the supplementalenhancement information message, when processing both the depthcomponent of the view component and the texture component of the viewcomponent. Router 36 may, in this instance, process the texturecomponent of the view component based on the supplemental enhancementinformation message and the nested supplemental enhancement informationmessage.

In some instances, when determining whether the nested supplementalenhancement information message applies in addition to the supplementalenhancement information message when coding the texture component of theview component, router 36 may determine that the nested supplementalenhancement information message only applies in addition to thesupplemental enhancement information message when coding the depthcomponent of the view component and not the texture component of theview component. As a result, router 36 may process the texture componentof the view component based on the supplemental enhancement informationmessage and not based on the nested supplemental enhancement informationmessage.

It should also be understood that FIG. 7 merely provides one example.That is, the steps shown in the example of FIG. 7 need not necessarilybe performed in the order shown in FIG. 7, and fewer, additional, oralternative steps may be performed.

FIG. 8 is a flow diagram illustrating example operation of a videocoding device in separately removing texture and depth components from adecoded picture buffer in accordance with the techniques described inthis disclosure. The example shown in FIG. 8 is generally described asbeing performed by video decoder 30 (FIGS. 1 and 3). However, it shouldbe understood that the process described with respect to FIG. 8 may becarried out by a variety of other processors, processing units,hardware-based coding units such as encoder/decoders (CODECs), and thelike.

In general, video decoder 30 may store a depth component and a texturecomponent of a view component (specified by multiview video data) in adecoded picture buffer, which is shown as reference picture memory 92 inthe example of FIG. 3 (150). Video decoder 30 may then analyze a viewdependency to determine whether the depth component is used forinter-view prediction (where such view dependency may be reflected abovewith respect to the example of FIG. 5; 152). Video decoder 30 mayanalyze this view dependency only for the depth component and separatelyanalyze a view dependency when attempting to remove the associatedtexture component from reference picture memory 92. In some instances,the view dependency is signaled in a multiview video coding sequenceparameter set extension of a subset sequence parameter set. The subsetsequence parameter set may contain a three dimensional video profile andis activated as an active view multiview video coding sequence parameterset when analyzing the view dependency. In any event, video decoder 30may then remove the depth component from reference picture memory 92without removing the texture component in response to determining thatthe depth component is not used for inter-view prediction (154).

Prior to removing this depth component, video decoder 30 may qualify thedepth component as eligible for removal by determining that the depthcomponent does not belong to a target output view and is associated witha network abstraction layer reference identification code having a valueequal to zero. As a result of potentially providing separate handling ofdepth and texture components, video decoder 30 may determine one or morereference pictures for the depth component that are different from thetexture component. That is, video decoder 30 may determine the one ormore reference pictures for the depth component by, at least,determining a reference picture list that identifies the one or morereference pictures for the depth component and determining a referencepicture list that identifies one or more additional reference picturesfor the texture component, wherein the one or more additional referencepictures determined for the texture component are different than the oneor more reference pictures determined for the depth component.

In determining the reference picture list for the depth component videodecoder 30 may determine the reference picture list for the depthcomponent and the texture component based on markings of the depth andtexture components by video encoder 20, which are used to identify thereference picture list for the depth component separately from markingthe texture component. In some instances, one or more syntax elementsmay be used to separately mark the depth component with the referencepicture list determined for the depth component and one or more syntaxelements are used to separately mark the texture component with thereference picture list determined for the texture component.

In some instances, video decoder 30 may determine that the depthcomponent and the texture component belong to a target output view to beoutput for display and simultaneously or nearly simultaneously outputthe depth component and the texture component.

It should be understood that the steps shown and described with respectto the example of FIG. 8 are provided as merely one example. That is,the steps shown in the example of FIG. 8 need not necessarily beperformed in the order shown in FIG. 8, and fewer, additional, oralternative steps may be performed.

FIG. 9 is a flow diagram illustrating example operation of a videocoding device in determining sequence level information forMVC-compatible 3DVC in accordance with the techniques described in thisdisclosure. The example shown in FIG. 8 is generally described as beingperformed by video decoder 30 (FIGS. 1 and 3). However, it should beunderstood that the process described with respect to FIG. 8 may becarried out by a variety of other processors, processing units,hardware-based coding units such as encoder/decoders (CODECs), and thelike.

As described above, video decoder 30 may determine first sequence levelinformation describing characteristics of the depth components anddetermining second sequence level information describing characteristicsof an operation point of the video data (160, 162). Moreover, videodecoder 30 may determining a reference picture list that identifies oneor more reference pictures for the depth components indicated in thethree-dimensional video coding sequence parameter set.

In some examples, the second sequence level information includes athree-dimensional video coding sequence parameter set that described,for the operation point, a list of target output views, a number oftexture views to be decoded when decoding the operation point, and anumber of depth views to be decoded for when decoding the operationpoint, where the number of texture views to be decoded is different formthe number of depth views. In some examples, video decoder 30 mayfurther target, for each of the target output views specified in thelist of target output views, the one or more depth components whenavailable.

In some examples, video decoder 30 may specify a three-dimensional videocoding scalability information SEI message as part of the video data,wherein three-dimensional video coding scalability information SEImessage includes a description of the operation point without the depthcomponents or a description of the operation point with the depthcomponents. In some instances, the SEI message includes an indication ofwhether the operation point includes the depth components. Moreover, insome examples, the SEI message includes an indication of whether theoperation point includes the depth components and directly dependentdepth views with directly dependent texture views for the decoding ofthe operation point.

It should be understood that the steps shown and described with respectto the example of FIG. 9 are provided as merely one example. That is,the steps shown in the example of FIG. 9 need not necessarily beperformed in the order shown in FIG. 9, and fewer, additional, oralternative steps may be performed.

While certain syntax elements described with respect to this disclosurehave been provided example names for purposes of explanation, it shouldbe understood that the concepts described in this disclosure are moregenerally applicable to any syntax elements, regardless of name. Forexample, while certain aspects refer to a “view order index,”“view_order_index” or “view_idx,” it should be understood that such asyntax element may be given an alternative name in a future codingstandard.

While certain techniques of this disclosure are described with respectto the H.264 standard, it should be understood that the techniques arenot necessarily limited to a particular coding standard. That is, thetechniques more generally relate to achieving coding efficiencies in3DVC, for example, through shorter and/or less complex NAL units andparameter sets, as described above.

It should be understood that, depending on the example, certain acts orevents of any of the methods described herein can be performed in adifferent sequence, may be added, merged, or left out altogether (e.g.,not all described acts or events are necessary for the practice of themethod). Moreover, in certain examples, acts or events may be performedconcurrently, e.g., through multi-threaded processing, interruptprocessing, or multiple processors, rather than sequentially. Inaddition, while certain aspects of this disclosure are described asbeing performed by a single module or unit for purposes of clarity, itshould be understood that the techniques of this disclosure may beperformed by a combination of units or modules associated with a videocoder.

In one or more examples, the functions described may be implemented inhardware, software, firmware, or any combination thereof. If implementedin software, the functions may be stored on or transmitted over as oneor more instructions or code on a computer-readable medium and executedby a hardware-based processing unit. Computer-readable media may includecomputer-readable storage media, which corresponds to a tangible mediumsuch as data storage media, or communication media including any mediumthat facilitates transfer of a computer program from one place toanother, e.g., according to a communication protocol.

In this manner, computer-readable media generally may correspond to (1)tangible computer-readable storage media which is non-transitory or (2)a communication medium such as a signal or carrier wave. Data storagemedia may be any available media that can be accessed by one or morecomputers or one or more processors to retrieve instructions, codeand/or data structures for implementation of the techniques described inthis disclosure. A computer program product may include acomputer-readable medium.

By way of example, and not limitation, such computer-readable storagemedia can comprise RAM, ROM, EEPROM, CD-ROM or other optical diskstorage, magnetic disk storage, or other magnetic storage devices, flashmemory, or any other medium that can be used to store desired programcode in the form of instructions or data structures and that can beaccessed by a computer. Also, any connection is properly termed acomputer-readable medium. For example, if instructions are transmittedfrom a website, server, or other remote source using a coaxial cable,fiber optic cable, twisted pair, digital subscriber line (DSL), orwireless technologies such as infrared, radio, and microwave, then thecoaxial cable, fiber optic cable, twisted pair, DSL, or wirelesstechnologies such as infrared, radio, and microwave are included in thedefinition of medium.

It should be understood, however, that computer-readable storage mediaand data storage media do not include connections, carrier waves,signals, or other transient media, but are instead directed tonon-transient, tangible storage media. Disk and disc, as used herein,includes compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and blu-ray disc where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.Combinations of the above should also be included within the scope ofcomputer-readable media.

Instructions may be executed by one or more processors, such as one ormore digital signal processors (DSPs), general purpose microprocessors,application specific integrated circuits (ASICs), field programmablelogic arrays (FPGAs), or other equivalent integrated or discrete logiccircuitry. Accordingly, the term “processor,” as used herein may referto any of the foregoing structure or any other structure suitable forimplementation of the techniques described herein. In addition, in someaspects, the functionality described herein may be provided withindedicated hardware and/or software modules configured for encoding anddecoding, or incorporated in a combined codec. Also, the techniquescould be fully implemented in one or more circuits or logic elements.

The techniques of this disclosure may be implemented in a wide varietyof devices or apparatuses, including a wireless handset, an integratedcircuit (IC) or a set of ICs (e.g., a chip set). Various components,modules, or units are described in this disclosure to emphasizefunctional aspects of devices configured to perform the disclosedtechniques, but do not necessarily require realization by differenthardware units. Rather, as described above, various units may becombined in a codec hardware unit or provided by a collection ofinteroperative hardware units, including one or more processors asdescribed above, in conjunction with suitable software and/or firmware.

Various aspects of the disclosure have been described. These and otheraspects are within the scope of the following claims.

What is claimed is:
 1. A method of coding video data including a viewcomponent comprising a depth component and a texture component, themethod comprising: activating a parameter set as a texture parameter setfor the texture component of the view component; and coding the texturecomponent of the view component based on the activated texture parameterset.
 2. The method of claim 1, further comprising: activating aparameter set for the depth component of the view component; and codingthe depth component of the view component based on the parameter setactivated for the depth component of the view component and not theactivated texture parameter set.
 3. The method of claim 2, furthercomprising activating a picture parameter set as a depth pictureparameter set for the depth view component of the video data.
 4. Themethod of claim 1, wherein coding the texture component of the viewcomponent comprises coding only the texture component of the viewcomponent and not the depth component of the view component based on theactivated texture parameter set.
 5. The method of claim 1, furthercomprising activating a texture sequence parameter set for coding thetexture view component and all other texture view components of thevideo data within a same view of the video data.
 6. The method of claim1, further comprising activating a depth sequence parameter set forcoding the depth view component and all other depth view components ofthe video data based within a same view of the video data.
 7. The methodof claim 1, further comprising activating a picture parameter set as aview picture parameter set for the texture view component of the videodata.
 8. The method of claim 1, wherein coding the texture componentcomprises encoding, with a video encoder, the texture component of theview component based on the activated texture parameter set.
 9. Themethod of claim 1, wherein coding the texture component comprisesdecoding, with a video decoder, the texture component of the viewcomponent based on the activated texture parameter set.
 10. The methodof claim 1, wherein the depth component and the texture component havedifferent resolutions.
 11. The method of claim 1, wherein the video dataconforms to a three-dimensional video coding extension to aH.264/Advanced Video Coding standard and is backwards compatible with amultiview video coding extension to the H.264/Advanced Video Codingstandard.
 12. A video coding device for coding video data including aview component comprised of a depth component and a texture component,the video coding device comprising: a processor configured to activate aparameter set as a texture parameter set for the texture component ofthe view component, and code the texture component of the view componentbased on the activated texture parameter set.
 13. The video codingdevice of claim 12, wherein the processor is further configured toactivate a parameter set for the depth component of the view component,and code the depth component of the view component based on theparameter set activated for the depth component of the view componentand not the activated texture parameter set.
 14. The video coding deviceof claim 13, wherein the processor is further configured to activate apicture parameter set as a depth picture parameter set for the depthview component of the video data.
 15. The video coding device of claim12, wherein the processor is further configured to, when coding thetexture component of the view component, code only the texture componentof the view component and not the depth component of the view componentbased on the activated texture parameter set.
 16. The video codingdevice of claim 12, wherein the processor is further configured toactivate a texture sequence parameter set for coding the texture viewcomponent and all other texture view components of the video data withina same view of the video data.
 17. The video coding device of claim 12,wherein the processor is further configured to activate a depth sequenceparameter set for coding the depth view component and all other depthview components of the video data based within a same view of the videodata.
 18. The video coding device of claim 12, wherein the processor isfurther configured to activate a picture parameter set as a view pictureparameter set for the texture view component of the video data.
 19. Thevideo coding device of claim 12, wherein the processor is furtherconfigured to, when coding the texture component, encode the texturecomponent of the view component based on the activated texture parameterset.
 20. The video coding device of claim 12, wherein the processor isfurther configured to, when coding the texture component, decode thetexture component of the view component based on the activated textureparameter set.
 21. The video coding device of claim 12, wherein thedepth component and the texture component have different resolutions.22. The video coding device of claim 12, wherein the video data conformsto a three-dimensional video coding extension to a H.264/Advanced VideoCoding standard and is backwards compatible with a multiview videocoding extension to the H.264/Advanced Video Coding standard.
 23. Avideo coding device for coding video data including a view componentcomprised of a depth component and a texture component, the video codingdevice comprising: means for activating a parameter set as a textureparameter set for the texture component of the view component; and meansfor coding the texture component of the view component based on theactivated texture parameter set.
 24. The video coding device of claim23, further comprising: means for activating a parameter set for thedepth component of the view component; and means for coding the depthcomponent of the view component based on the parameter set activated forthe depth component of the view component and not the activated textureparameter set.
 25. The video coding device of claim 23, furthercomprising means for activating a picture parameter set as a depthpicture parameter set for the depth view component of the video data.26. The video coding device of claim 23, wherein the means for codingthe texture component of the view component comprises means for codingonly the texture component of the view component and not the depthcomponent of the view component based on the activated texture parameterset.
 27. The video coding device of claim 23, further comprising meansfor activating a texture sequence parameter set for coding the textureview component and all other texture view components of the video datawithin a same view of the video data.
 28. The video coding device ofclaim 23, further comprising means for activating a depth sequenceparameter set for coding the depth view component and all other depthview components of the video data based within a same view of the videodata.
 29. The video coding device of claim 23, further comprising meansfor activating a picture parameter set as a view picture parameter setfor the texture view component of the video data.
 30. The video codingdevice of claim 23, wherein the depth component and the texturecomponent have different resolutions.
 31. The video coding device ofclaim 23, wherein the video data conforms to a three-dimensional videocoding extension to a H.264/Advanced Video Coding standard and isbackwards compatible with a multiview video coding extension to theH.264/Advanced Video Coding standard.
 32. A non-transitorycomputer-readable storage medium having stored thereon instructionsthat, when executed, cause one or more processors of a video codingdevice to: activate a parameter set as a texture parameter set for thetexture component of the view component; and code the texture componentof the view component based on the activated texture parameter set. 33.The non-transitory computer-readable storage medium of claim 32, furtherhaving stored thereon instructions that, when executed cause the one ormore processors to: activate a parameter set for the depth component ofthe view component; and code the depth component of the view componentbased on the parameter set activated for the depth component of the viewcomponent and not the activated texture parameter set.
 34. Thenon-transitory computer-readable storage medium of claim 33, furtherhaving stored thereon instructions that, when executed cause the one ormore processors to activate a picture parameter set as a depth pictureparameter set for the depth view component of the video data.
 35. Thenon-transitory computer-readable storage medium of claim 32, wherein theinstructions that, when executed, cause the one or more processors tocode the texture component of the view component comprise instructionsthat, when executed, cause the one or more processors to code only thetexture component of the view component and not the depth component ofthe view component based on the activated texture parameter set.
 36. Thenon-transitory computer-readable storage medium of claim 32, furtherhaving stored thereon instructions that, when executed cause the one ormore processors to activate a texture sequence parameter set for codingthe texture view component and all other texture view components of thevideo data within a same view of the video data.
 37. The non-transitorycomputer-readable storage medium of claim 32, further having storedthereon instructions that, when executed cause the one or moreprocessors to activate a depth sequence parameter set for coding thedepth view component and all other depth view components of the videodata based within a same view of the video data.
 38. The non-transitorycomputer-readable storage medium of claim 32, further having storedthereon instructions that, when executed cause the one or moreprocessors to activate a picture parameter set as a view pictureparameter set for the texture view component of the video data.
 39. Thenon-transitory computer-readable storage medium of claim 32, wherein theinstructions that, when executed, cause the one or more processors tocode the texture component comprise instructions that, when executed,cause the one or more processors to encode the texture component of theview component based on the activated texture parameter set.
 40. Thenon-transitory computer-readable storage medium of claim 32, wherein theinstructions that, when executed, cause the one or more processors tocoding the texture component comprise instructions that, when executed,cause the one or more processors to decode the texture component of theview component based on the activated texture parameter set.
 41. Thenon-transitory computer-readable storage medium of claim 32, wherein thedepth component and the texture component have different resolutions.42. The non-transitory computer-readable storage medium of claim 32,wherein the video data conforms to a three-dimensional video codingextension to a H.264/Advanced Video Coding standard and is backwardscompatible with a multiview video coding extension to the H.264/AdvancedVideo Coding standard.